VOIP Cutover Checklist: How to Switch Without Missing Calls (2026)

The VOIP cutover is the moment you switch from your old phone system to your new one. It is the highest-risk point in any migration, and most failures happen here, not in the planning phase. The provider sets up the new system, the number port goes through, and suddenly no one can make or receive calls. This checklist covers every phase from four weeks out to 48 hours after cutover, so you know exactly what to do and when. It is based on real deployment patterns across Australian small businesses on NBN connections, including the specific failure modes that catch people out. By the end, you will have a repeatable process you can hand to a staff member or IT contact.

Why VOIP Cutovers Go Wrong

Most VOIP problems are not technical failures. They are sequencing failures. The new system is configured correctly, the number port is submitted, the phones are on the desk. But no one tested inbound calls before the port went live. No one confirmed the after-hours routing pointed at the right voicemail. No one told the receptionist that the hold button is now on the left side of the phone, not the right.

The other common failure is timing. Number ports do not complete on a schedule you control. You submit a port and the carrier processes it when they process it, usually within the window you agreed on, but not always at the exact minute you planned. If you cancel your old service the day before the port and the port is delayed, your number is unreachable for hours or longer.

This checklist is structured to prevent both failure types. It separates testing from porting, puts parallel operation periods in place, and includes explicit timing guidance for when NOT to cut over.

Phase 1: Pre-Cutover Preparation (4-6 Weeks Out)

This phase is about building the new system alongside the old one without touching the old one. Nothing is switched over yet. You are just building and testing in parallel.

Confirm Your NBN Connection Is VOIP-Ready

VOIP runs over your internet connection. If the connection has high jitter, packet loss, or insufficient upload bandwidth, call quality will be poor regardless of how well everything else is configured. Check these basics before committing to a cutover date.

Each concurrent VOIP call needs approximately 100 Kbps of upload bandwidth using the G.711 codec (standard quality). A business with 4 simultaneous calls needs 400 Kbps of upload, plus headroom for other traffic. Most NBN connections have plenty of bandwidth for this, but FTTN connections with 5-10 Mbps upload can get tight if people are also uploading files or using cloud backups. Use the VOIP bandwidth calculator to check your specific situation before the cutover.

Jitter and packet loss matter more than raw speed. A 100 Mbps connection with 50ms jitter will produce choppy calls. A 12 Mbps FTTN connection with stable jitter under 20ms will produce clear calls. If you are on HFC or FTTN, run a continuous ping test to your VOIP provider's SIP server for 10 minutes during business hours. If you see packet loss or latency spikes, fix the connection issue before the cutover, not after. See the NBN VOIP compatibility guide for details by connection type.

Choose and Test Hardware Before Cutting Over

Order your new VOIP phones 4-6 weeks before the planned cutover. You need time to configure them, test them on the new system, and train staff. Arriving with unconfigured phones on cutover day is a common and avoidable mistake.

Most Australian VOIP providers can pre-configure phones before shipping (auto-provisioning). This means the phone boots up, contacts the provider's server, and downloads its configuration automatically. You plug it in, it registers, and it is ready. Confirm this with your provider before ordering. Pre-configured phones reduce on-site setup time from hours to minutes.

If you are sourcing phones separately, you will need to manually enter the SIP credentials your provider gives you. Allow 20-30 minutes per phone for someone who has done it before, longer for a first-timer. Plan this into your timeline. See the best SIP desk phones guide for phone recommendations that work well with Australian providers.

Set Up the New System in Parallel

The new system should be live and operational on a separate number (a temporary number your provider gives you, or a new number you have not yet ported) before you touch your existing numbers. This lets you test everything fully without any risk to your current calls.

During this parallel phase, configure everything you will need on the production system: call flows, IVR menus, ring groups, hunt groups, voicemail, and after-hours routing. Do not leave this for cutover day. Every minute spent configuring on cutover day is a minute your phones are not fully operational.

Configure Call Flows and Routing

Map out exactly what should happen to every inbound call before you configure anything. Answer these questions in writing, then build the routing to match:

During business hours: Does the call go straight to a specific person, to a ring group (all phones ring simultaneously), to a hunt group (phones ring in sequence), or to an IVR menu first? What happens if no one answers? Does it go to voicemail, to another extension, or to a mobile?

After hours: Does the caller hear a recorded message with your hours, get forwarded to voicemail, or get routed to a mobile? If you use a 1300 number, does it route differently after hours than during business hours?

Holiday routing: Some VOIP systems let you pre-configure routing for specific dates. Set this up during the parallel phase so you are not doing it in a hurry on the day before a public holiday.

Set Up All Extensions and Test Each One

Create a user account and extension for every person who needs a phone. Do not create them all on cutover day. Create them now, test each extension by calling it from another extension and confirming the phone rings and the call connects clearly. Log the extension number and the user's name in a simple spreadsheet. This becomes your go-to reference on cutover day.

Submit the Number Port

Number porting is the process of transferring your existing phone numbers to the new VOIP provider. In Australia, a standard geographic number port takes 3-10 business days once the Letter of Authorisation (LOA) is submitted and accepted. The exact timing depends on your current carrier and whether the details on the LOA match your account records exactly.

Submit the port 3-4 weeks before your planned cutover. This gives you time to correct any rejection issues without the cutover date becoming a crisis. The port will complete when it completes. You cannot always control the exact date, only the approximate window. See the number porting guide and the porting timeline guide for the full process.

Phase 2: One Week Before Cutover

By this point the new system is built and configured. This week is about verification, communication, and fallback planning.

Notify Staff

Tell every person who uses a phone what is changing, when it is changing, and what will be different. Keep it simple. Three things they need to know: their new extension number, how to transfer a call, and how to access voicemail. Everything else can wait for the first week of operation.

If you have a receptionist who handles most inbound calls, spend an hour with them specifically on the new system during this week. They will encounter the most edge cases on cutover day. The more confident they are, the smoother the cutover will feel to callers.

Full System Test

Use the temporary number assigned during the parallel setup phase to test every call scenario on the new system. Do not skip any of these:

Inbound calls during business hours: Call the temporary number from an external mobile. Confirm it rings the correct destination, the call connects clearly, and you can speak and hear properly in both directions.

Inbound calls after hours: Change the system time to simulate after-hours (or use a test mode if your provider offers one) and call again. Confirm the after-hours routing works correctly. Hear the after-hours message if applicable. Confirm voicemail is recording messages and notifications are being sent.

Outbound calls: Make a call from each extension to an external mobile. Confirm the correct caller ID is displayed. Confirm the call connects and both parties can hear clearly. Confirm the outbound number is displaying as your business number, not a random number from your provider's pool.

Call transfers: Test attended transfer (you speak to the recipient before transferring) and blind transfer (you transfer without speaking to the recipient). Both need to work. A failed transfer that drops the caller is a serious problem.

Hold and resume: Put a call on hold from each extension and confirm music on hold plays for the caller. Resume the call and confirm audio reconnects cleanly.

Voicemail: Leave a voicemail on an extension and confirm the notification is sent (email, SMS, or both, depending on how you configured it). Check the message plays back clearly.

Confirm Internet Bandwidth

Run a speed test during business hours (not overnight when usage is low) and note your actual upload and download speeds. Compare against the bandwidth requirements for your number of concurrent calls. If you are close to the limit, talk to your provider about codec options. G.729 compresses calls to about 32 Kbps each, roughly a third of G.711 bandwidth, with slightly lower audio quality. For congested connections, it is a useful option.

Have a Fallback Plan

Write down the mobile numbers for every key staff member. If the cutover has a problem and phones are unreachable for 30 minutes, you need to be able to reach people and divert critical calls to mobiles. Put this list somewhere physical (printed) so it is accessible even if your internet is down.

If you have a 1300 number or other smart number, confirm with your provider how to update the routing endpoint quickly if needed. A 1300 number routes to a geographic number or VOIP endpoint that you control. If the VOIP system has a problem, you can redirect the 1300 to a mobile within minutes. Know the process before you need it.

Phase 3: Cutover Day Checklist

Cutover day is a verification exercise, not a build exercise. Everything should already be built and tested. Your job today is to confirm every system is working correctly once the ported numbers are live.

Work through this checklist in order. Do not skip steps or reorder them. If a step fails, stop and resolve it before moving to the next step.

Step 1: Confirm All Phones Are Registered

Log into your VOIP provider's admin portal or PBX interface and check the registration status of every phone. A registered phone shows a green icon or "Online" status. An unregistered phone will not receive or make calls. If any phones show as unregistered, resolve this before the port completes. Common causes: the phone lost power overnight, the network has a DHCP issue, or the SIP credentials on the phone do not match the account.

Step 2: Test Calls from Each Extension

Call extension to extension on every phone in the office. Confirm each phone rings, each call connects, and audio is clear in both directions. This takes about 2 minutes and catches any phones that are registered but not functioning correctly.

Step 3: Test Incoming Calls from External Mobile

Once the port completes, call your ported number from a mobile that is NOT on the same network (use a personal mobile on a different carrier to your business connection). Confirm the call arrives at the correct destination, rings the correct phones, and audio is clear.

If you have multiple numbers (main number, direct lines for specific staff, a 1300 number), test each one. Do not assume that because one number works, all numbers work. They can have different routing configurations.

Step 4: Test Outbound Calls and Caller ID

Make an outbound call from the main reception phone or the primary extension. Check on the receiving phone what number displays. It should show your business number, not a random number. If the wrong caller ID is showing, contact your provider immediately. Callers receiving calls from an unknown number will not answer, and callbacks to the number that called them will not reach you.

Step 5: Test Voicemail

Call your main number from an external mobile and let it go to voicemail. Leave a test message. Confirm the voicemail notification arrives (email with attachment or SMS notification). Play the message back. Confirm the audio is clear and the message is the one you just left, not a cached message from the old system.

Step 6: Test After-Hours Routing

Either wait until after business hours or temporarily activate after-hours mode in your VOIP system. Call your main number and confirm the after-hours routing works as configured. If it is supposed to play a message and send calls to voicemail, confirm that happens. If it forwards to a mobile after hours, confirm the forward works.

Step 7: Confirm Port Completion with Provider

Contact your VOIP provider and confirm the number port is fully complete. Ask them to confirm each number individually if you ported more than one. Get written confirmation (email or portal record). You will need this if there is any dispute later about when the port completed and whether your old carrier correctly released the numbers.

Step 8: Brief Staff on New System

Gather staff for a brief 10-minute walkthrough of the new system. Show them the extension list, how to transfer calls, how to access voicemail, and how to put a call on hold. Keep it short. Distribute the printed extension list. Tell them who to call if something does not work (you, or your provider's support line).

Phase 4: Post-Cutover (First 48 Hours)

The first 48 hours are the highest-risk period. Most problems that were missed in testing will surface here. Stay available and monitor actively.

Monitor Call Quality

Ask staff to flag any calls that sound choppy, robotic, or where one party cannot be heard. One or two minor issues in the first hour is normal as the system settles. Repeated quality issues on multiple phones suggest a network or configuration problem that needs attention. Log the time of each issue and which extension it occurred on. This information helps your provider diagnose the cause.

Most VOIP providers show call quality metrics in their portal (MOS scores, jitter, packet loss per call). Check these after the first day to get a baseline for your connection quality. If MOS scores are consistently below 3.5 or packet loss is above 1%, escalate with your provider.

Check Voicemail Delivery

Confirm voicemail notifications are being received. It is easy to overlook a voicemail configuration issue in the first 24 hours because staff are focused on the phones working. Have someone check the voicemail email inbox specifically and confirm messages are arriving.

Confirm No Calls Are Dropping

A specific failure mode worth watching for: calls that connect but drop after exactly 30 seconds or 60 seconds. This is almost always caused by SIP ALG on the router, which rewrites SIP packets in a way that breaks the call keepalive. The fix is to disable SIP ALG on your router. This is found under firewall, NAT, or advanced settings on most routers.

Do Not Cancel Your Old Service Yet

Wait at least 24 hours of successful operation on the new system before cancelling your old service. Ideally wait a full business day. The old service is your safety net. If the new system has a serious problem in the first 24 hours, the old service can be reactivated relatively quickly (though not instantly). Once it is cancelled, that option is gone.

When you do cancel, confirm in writing. Old phone services sometimes continue billing for months after verbal cancellation. Get a cancellation confirmation reference number and the date the service will be disconnected.

When NOT to Cut Over

Timing matters. Some days are much higher risk than others for a VOIP cutover.

Avoid end of financial year (June) and tax season. Your staff are under higher workload. An IT disruption hits harder. If something goes wrong, the business consequences are more severe because of the call volume at that time of year.

Avoid Monday mornings. Staff are catching up from the weekend. Inbound call volume is typically highest on Monday mornings. A system issue on the first two hours of a Monday will affect more callers than the same issue mid-afternoon on a Wednesday.

Avoid public holiday windows. If your cutover date falls within two business days of a public holiday, reschedule. Port processing can slow around public holidays and provider support staffing is reduced.

The ideal cutover window: Tuesday or Wednesday morning, mid-month, no public holidays in the surrounding week. Cut over at 9am so you have a full business day to resolve any issues with full support staffing available.

Common Cutover Mistakes

Mistake 1: Testing After the Port Instead of Before

The most common failure: the new system is configured on the day of the port and tested after the port completes. Live calls are arriving while the testing is still happening. Issues that could have been caught and fixed in 20 minutes during the parallel phase now need to be resolved with customers waiting. Build and test on the temporary number first. Port second. Always.

Mistake 2: Cutting Over on a Friday

Friday afternoon cutovers are extremely common because it feels like a natural end-of-week clean break. It is not. It is the worst possible time. If the system has a problem, you are dealing with it over the weekend with reduced or no provider support. Do not let anyone talk you into a Friday cutover, including your VOIP provider.

Mistake 3: Cancelling the Old Service Too Early

Some businesses cancel their old phone service as part of the port process, thinking the port replaces it. The port transfers your number to the new service. The old service (the billing account, the line rental, any additional numbers not being ported) is a separate cancellation. Keep the old service active until you have confirmed everything is working. Then cancel with written confirmation.

Mistake 4: Not Configuring After-Hours Routing

After-hours routing is easy to skip during setup because you configure the system during business hours and never experience the after-hours state. Then at 6pm on cutover day, calls to your number ring out with no voicemail and no message. Set up after-hours routing explicitly and test it before the cutover.

Mistake 5: Assuming Softphones Are Ready Without Testing

If your team is using softphones (apps on computers or mobiles rather than desk phones), they need to be installed, configured, and tested on each device before cutover. A softphone that works on one laptop may have audio device issues on another. Test every device individually. Battery-powered devices (laptops, mobiles) also need to be aware that VOIP requires an internet connection. Calls from a mobile softphone on a poor mobile data connection will have quality issues regardless of what your office NBN connection looks like.

What to Do If Something Goes Wrong

If phones stop working on cutover day, stay calm and work through this sequence. Most issues are resolved within 30 minutes.

1. Check registration status. Log into your provider's portal and confirm phones are showing as registered. If they are not registered, the issue is at the phone or network level, not the provider's platform. Check network connectivity, restart the phone.

2. Test from a softphone. Install your provider's softphone app on your mobile and log in with your extension credentials. If the softphone works but desk phones do not, the issue is with the phones or the office network, not the VOIP service.

3. Check the number port status. Contact your provider and ask for the port status on your number. If the port has not yet completed, calls are still going to the old system. The old system should still be active. Make sure it is still running and not already cancelled.

4. Activate your fallback plan. Forward your main number to mobile if the VOIP system is unresponsive. If you have a 1300 number, redirect it to a mobile number. Calls keep flowing while you resolve the underlying issue.

5. Call your provider's support line. Give them the specifics: which numbers are affected, what symptoms you are seeing, when it started, and what the registration status shows. A good VOIP provider can usually diagnose a cutover issue within minutes. This is why provider support quality matters. Check support hours and response time SLAs before you sign up, not after.

Australian-Specific Considerations

Number porting in Australia: Australian number ports are regulated by ACMA and governed by the Telecommunications Numbering Plan. Geographic numbers (02, 03, 07, 08) have slightly different port processes than mobile numbers. 1300 and 1800 numbers are inbound number ports and follow their own process. Port rejections are common when account details do not exactly match the carrier's records. Confirm your account holder name, account number, and service address with your current carrier before submitting the LOA. See the Cat A vs Cat C porting guide for the technical classification of your port.

PSTN shutdown impact: Australia's copper PSTN network was shut down in 2025. If you are still on a copper landline (unlikely at this point, but possible in some regional areas), your migration is not optional. The service has been or will be disconnected. VOIP on NBN is the replacement. This also means that anyone still on a traditional PABX attached to PSTN lines needs to migrate. See the PSTN shutdown guide for what this means for your specific setup.

Power outages and VOIP: VOIP phones require both power and internet to work. During a power outage, your VOIP phones go down unless you have battery backup (UPS) on the NBN equipment and phones. Traditional copper phones worked during a power outage because power came down the line. VOIP does not. If your business needs call capability during power failures (a medical clinic, for example), you need a UPS on the NBN gateway and router, or you need to configure mobile forwarding as an automatic fallback when VOIP is unreachable.

000 emergency calling on VOIP: VOIP providers in Australia are required to provide access to 000 emergency services. However, the call may not automatically transmit your location to the emergency operator the way a traditional phone does. Confirm with your provider how 000 is handled on your service. Brief staff that if they call 000 from a VOIP phone, they should state their address clearly at the start of the call.

If you are migrating from a traditional landline or ISDN system, the landline to VOIP migration guide and the ISDN to VOIP migration guide cover the specific steps and considerations for those transitions.

What Most Businesses Get Wrong

They treat the cutover as the deadline, not the test phase. Businesses spend weeks preparing the new system and then treat cutover day as the first real test. It should be the last test. Everything should already be verified on the temporary number. Cutover day is a confirmation exercise, not a setup exercise.

They let the old service lapse automatically. A fixed-term phone contract that expires on the day of your VOIP cutover sounds convenient but is dangerous. If the port is delayed by even one day, you have no phone service. Always choose to explicitly cancel the old service after confirming the new one works, rather than relying on contract expiry to time the transition.

They under-invest in the first week of support. The first week after cutover is not the time to reduce IT support. It is the time to increase it. Have someone available to take calls from staff about the new system. Most questions are simple, but if staff cannot get answers quickly, they lose confidence in the new system and productivity drops. Invest an hour a day in the first week to handle questions and tune the configuration.

Your Next Steps

Use this checklist to plan your cutover from the current week backward:

4-6 weeks out: Confirm NBN is VOIP-ready. Order and test phones. Set up new system on a temporary number. Submit number port LOA.

1 week out: Notify staff. Test all call scenarios on the temporary number. Confirm bandwidth. Print the extension list and fallback mobile numbers.

Cutover day (Tuesday or Wednesday morning): Check registrations. Test extensions. Confirm port. Test inbound and outbound. Brief staff.

First 48 hours: Monitor call quality. Check voicemail. Watch for dropped calls. Keep the old service active until you have confirmed 24 hours of clean operation.

If you are still choosing a VOIP provider, the best VOIP providers for Australian small business guide and the VOIP cost guide will help you work through that decision before you start the cutover process.

How long does a VOIP cutover take?

The cutover day itself takes 2-4 hours if everything is prepared in advance. This includes confirming phone registrations, running test calls from each extension, verifying inbound routing, and briefing staff. The preparation phase (parallel setup, testing, number port submission) takes 3-4 weeks. Trying to compress the preparation phase is the most common cause of cutover day problems.

Can I cut over on a Friday?

Technically yes, but it is strongly not recommended. VOIP provider support staffing is typically reduced over weekends. If something goes wrong on a Friday afternoon, you may not have full support until Monday. Cut over on a Tuesday or Wednesday morning so you have the full working day and full support access if problems arise.

What happens to calls during the number port?

During a geographic number port in Australia, there is a brief window (typically under an hour, sometimes just minutes) when the number transitions from the old carrier to the new one. Calls during this exact window may not connect. This is why you configure the new system first and test it on a temporary number. Once the port completes, calls arrive on the new system immediately. For 1300 numbers, the transition is typically smoother because the routing is updated at the smart number level.

What if my number port is rejected?

Port rejections in Australia are almost always caused by mismatched account details. The account holder name, account number, or service address on the LOA does not exactly match what the losing carrier has on file. Call your current carrier and confirm these details before resubmitting. Common issues: using a trading name instead of the registered business name, or a street address that does not match the billing address on the account. Resubmit as soon as possible after correcting the details, as rejections add 5-10 business days to your timeline.

Do I need to keep my old phone service during the cutover period?

Yes. Keep the old service active until you have at least 24 hours of successful operation on the new VOIP system. The old service is your fallback. If the number port is delayed, the old service catches calls in the meantime. Once you are confident the new system is working correctly, cancel the old service in writing and get a cancellation confirmation reference number.

What should I do if calls are dropping after the cutover?

Calls dropping at exactly 30 or 60 seconds is almost always SIP ALG on the router. Disable SIP ALG in your router settings (under firewall or advanced settings). Calls dropping randomly may be a network quality issue. Check your NBN connection bandwidth and jitter. Calls not connecting at all suggest the number port may not have fully completed, or a phone registration issue. Check the registration status of each phone in your provider's portal and call their support line with the specific symptoms.

Do VOIP phones work during a power outage?

No. VOIP phones require both power and internet to function. During a power outage, your NBN equipment, router, and VOIP phones all stop working. Traditional copper landlines worked during power outages because power was delivered over the phone line. VOIP does not have this. If you need phone capability during power failures, install a UPS (uninterruptible power supply) on your NBN gateway and router, or configure your 1300 number or main number to forward to a mobile automatically when VOIP is unreachable.