New IP Phone Setup Guide Australia: What to Do After You Buy a SIP Desk Phone

Related guides: What is VOIP? A plain English guide for Australian businesses, Best VOIP phone system for small business Australia, Best SIP desk phones available in Australia, ATA adapter guide: keeping analogue phones on VOIP, QoS and SIP ALG settings on Australian routers, NBN phone options for business: the three tiers explained

Why Your New IP Phone Shows 'Not Registered'

An IP desk phone is a terminal device, the equivalent of a screen without a computer behind it. To make and receive calls, it needs to connect to a VOIP service using SIP (Session Initiation Protocol). Registration-based SIP services commonly provide a server address, username and password. Other services may use a separate authentication ID, an outbound proxy or IP-based authentication, so use the exact settings supplied by the provider.

Until those credentials are entered, the phone has nothing to register with. 'Not Registered' is the phone's way of saying: I am ready, but I do not know who my business phone company is.

The NBN Phone Port: Why It Does Not Work With an IP Phone

Many businesses assume a new IP phone will plug into the phone port on the back of their NBN modem (typically the green port). It will not, and understanding why saves significant time and frustration.

If your business has been using the green port with a standard cordless phone, that service is ISP-controlled. Whether you can reuse the ISP service depends on the provider. Some providers keep the credentials managed inside their gateway, while others publish SIP credentials for compatible BYO VoIP equipment. Check the provider's BYO VoIP policy before purchasing a separate account.

What You Actually Need

Before you can make a call, you need four things:

1. A business phone company account. This is the service that gives you a phone number and routes your calls. Signing up typically takes 10-15 minutes online.

2. SIP credentials. Your provider gives you a SIP server address, SIP username, and SIP password. These go into the phone's configuration.

3. An Ethernet connection. Your IP phone connects to your router or network switch via an RJ45 cable, the same type used by computers. Do not plug it into the green phone port.

4. Power. Either a compatible power adapter, which may be sold separately, or a supported PoE switch can power the phone., which delivers power through the network cable.

If you need to power phones via Ethernet, see our guide on whether you need a PoE switch for VoIP phones.

Step 1, Choose a business phone company

Your business phone company is the company that handles your calls and issues the SIP credentials your phone needs. When evaluating AU providers, look for:

Month-to-month terms. Avoid lock-in contracts until you have confirmed the service suits your setup. Most reputable AU providers offer no-contract plans.

Auto-provisioning support for your phone brand. Some providers support automatic configuration of Yealink and Grandstream phones, the phone contacts the provider's server on first boot and downloads its own settings, no manual entry required. This is the easiest path if your provider supports it.

Transparent per-second or per-minute call rates. Look for clear AU pricing on the provider's website. Per-call flat rates penalise short calls; per-second billing is fairer for most business calling patterns.

Local number included. Confirm the provider can issue or port a number with your local area code, or a 1300 number if that is what your business needs.

For hardware, the Yealink T31P is a reliable entry-level SIP desk phone, and the Yealink T54W is a popular mid-range option with a colour touchscreen, both support standard auto-provisioning mechanisms, but provider-specific template support should be confirmed before purchase.

Step 2, Get Your SIP Credentials

After signing up, your provider will issue SIP credentials. These are typically provided via email or a self-service portal and consist of three items:

SIP Server / Proxy: the provider's SIP server address (for example, sip.yourprovider.com.au or a numeric IP address).

SIP Username / Extension: your account identifier or extension number.

SIP Password: the authentication password for your SIP account.

Step 3, Connect Your Phone to Your Network

IP phones connect via Ethernet (RJ45). Most phones include a secondary Ethernet port (labelled PC) that passes network connectivity through to a connected computer, so a single cable run can serve both the phone and a desktop PC.

Connection options:

Direct to router: Simplest setup for one or two phones. Run an Ethernet cable from the phone's WAN or LAN port to any available port on your router.

Via a network switch: For offices with multiple devices. Connect the phone to the switch the same as any other device.

PoE (Power over Ethernet): If your switch supports 802.3af PoE, the phone can draw power through the Ethernet cable. No separate power adapter needed.

Wi-Fi: Mid-range and high-end IP phones typically support 802.11n or 802.11ac Wi-Fi. Wired Ethernet is always preferable for call quality and registration stability. Use Wi-Fi only where cabling is not practical.

Step 4, Configure SIP Credentials

Option A: Auto-Provisioning (Easiest)

Some business phone companies support auto-provisioning for Yealink and Grandstream phones. When you connect the phone to your network, it contacts the provider's provisioning server and downloads its configuration automatically. No manual credential entry required.

To check if your provider supports this, look for 'auto-provisioning', 'zero-touch provisioning', or 'plug and play' on their website or sign-up portal. You may need to register your phone's MAC address (printed on the underside of the phone) in your provider's account portal first. Once registered, power the phone on and it should configure itself within a few minutes.

Option B: Manual SIP Configuration via Web Interface

If your provider does not support auto-provisioning, enter SIP credentials manually through the phone's web interface:

1. Find your phone's IP address. On most Yealink phones: press OK, then navigate to Status > Network. On Grandstream phones: press the Menu button and navigate to Status > Network Status.

2. Open your phone's admin page. On a computer connected to the same network, open a browser and type the phone's IP address into the address bar. Log in with the default admin credentials (Yealink: admin/admin; For current Grandstream GRP phones, use username “admin” and the random administrator password printed on the phone's label. Other Grandstream families may use different defaults, so check the model's manual or label.).

3. Navigate to the SIP account settings. Yealink: Account > Account 1. Grandstream: Accounts > Account 1.

4. Enter your SIP credentials. Fill in the SIP Server, SIP Username (or Auth Username if prompted separately), and SIP Password fields exactly as provided by your business phone company.

5. Save and confirm registration. After saving, the phone will attempt to register. The display should show your phone number or extension within 10 to 30 seconds if credentials are correct.

Step 5, Make a Test Call

Once the phone shows registered, confirm it is working correctly:

Outbound call: Dial your mobile number from the IP phone. Confirm the call connects and audio is clear in both directions.

Inbound call: Call the IP phone from your mobile. Confirm it rings and that you can answer.

Voicemail: Let a call go to voicemail to confirm the voicemail greeting is configured and messages can be retrieved.

If all three work, setup is complete.

Troubleshooting: Phone Still Shows 'Not Registered'

Check Your SIP Credentials First

The most common cause of registration failure is a credential typo. SIP passwords are case-sensitive. Re-enter the SIP server address, username, and password carefully. If your provider's portal shows a different format for the SIP server (e.g., with or without sip: prefix), try both. Confirm with your provider that the account is active and the credentials are correct before proceeding.

Disable SIP ALG on Your Router

SIP ALG (Application Layer Gateway) is a router feature that attempts to manage SIP traffic. On most Australian consumer routers and NBN gateways, it is enabled by default and frequently corrupts SIP signalling, preventing phones from registering.

Check Your Firewall

Firewall requirements are provider- and deployment-specific. SIP may use UDP, TCP or TLS on provider-defined ports, and the RTP audio range is configured by the phone, PBX or provider. Use the provider's and equipment manufacturer's documented port list. If your office is behind a managed firewall, common in commercial buildings with shared IT infrastructure, these ports may be blocked. Check with your IT administrator or building manager.

Check Your Internet Connection

A highly variable or unstable internet connection can cause intermittent registration drops. Run a speed test and ping test from the same network. Each simultaneous VOIP call requires approximately 100kbps of symmetrical bandwidth. For most businesses on NBN 25 or above, bandwidth is not the issue, latency stability is. If your ping varies significantly (high jitter), contact your ISP or look at your router's QoS settings to prioritise VOIP traffic.

Factory Reset as a Last Resort

If credentials are confirmed correct and SIP ALG is disabled but the phone still will not register, a factory reset and fresh configuration is sometimes faster than further troubleshooting. Yealink phones: Menu > Settings > Advanced Settings (password: admin) > Reset Config > Reset to Factory. Grandstream GRP phones: use the model's on-screen factory-reset menu. On GRP261x models, select Menu → System → Operations → Factory Reset; GRP260x menu paths differ, so consult the exact model's guide. After reset, re-enter credentials from scratch.

Troubleshoot the symptom before changing codecs. For one-way or missing audio, first check RTP reachability, routing, NAT and firewall settings. Codec negotiation is one possible cause of failed or degraded audio, but echo and choppiness can have different causes. Most AU VOIP providers prefer G.711 (also listed as G.711a, PCMA, or PCMU) for clarity on fast connections, or G.729 for lower bandwidth usage. Yealink phones enable G.711 by default. Grandstream GRP series phones may have a different codec priority order in their default configuration. Find codec settings under Account Settings in the phone's web interface (access at the phone's IP address in a browser). If your provider's documentation specifies a preferred codec, set it explicitly and prioritise it. G.711 requires approximately 80 to 90 kbps of actual network bandwidth per concurrent call including overhead. G.729 reduces this to approximately 32 kbps, which can matter on congested connections but may affect audio clarity with some providers.The SIP credential field names differ between phone manufacturers, which causes confusion when following a provider's generic setup guide. On Yealink phones (T-series and W-series), the main SIP account fields under Account tab are: Display Name, Register Name (your SIP username), Username (also your SIP username, same value), Password, SIP Server (your provider's SIP domain), and Port (5060 for UDP, 5061 for TLS). On Grandstream GRP series phones, the equivalent fields under Account are: SIP Server, SIP User ID, Authenticate ID (same as SIP User ID in most cases), Authenticate Password, and Name. If a provider guide says "SIP user" and your phone says "Register Name", they refer to the same thing. Enter each field exactly as supplied by the provider. SIP User ID and Authenticate ID are sometimes identical, but they can be different; do not duplicate values unless the provider's instructions say to do so.

What Does IP Phone Setup Cost?

The phone itself is the main cost: entry-level SIP desk phones start at $70-120 (inc. GST) in Australia. Australian hosted-PBX and SIP-service pricing varies widely by provider, plan type, call inclusions, phone-number charges and support level; verify current total per-user and account-level costs. Auto-provisioning may reduce configuration work, but any setup or hardware-provisioning fee depends on the provider and plan. If you need technical support for manual SIP credential entry, most providers charge $0-50 for that call. Firmware updates may be automatic on a provider-managed or correctly provisioned phone, but unmanaged phones can require manual update configuration. Hardware replacement, accessories and power equipment can also create later costs.

If your IP phone is Yealink or Grandstream and you want to confirm which AU VOIP providers support auto-provisioning for those models without manual SIP configuration, see VOIP Providers That Work With Yealink and Grandstream Phones in Australia.

Do I need a phone system (PBX) to use one IP phone?

Some registration-based SIP services allow a compatible IP phone to connect directly without a PBX. Other SIP trunks require a PBX, SBC, static-IP peering or accredited equipment, and features such as voicemail depend on the service plan. A PBX adds features like multiple extensions, auto-attendant (IVR) menus, ring groups, and call recording, useful for businesses with two or more staff handling calls together, but not required for a single phone setup. See our best VOIP phone system for small business guide for the full comparison.

Why can't I use the phone port on my NBN modem with a new IP phone?

The phone port on your NBN modem (typically green) is an analogue FXS output connected to your ISP's own VOIP service. It is designed exclusively for traditional analogue handsets. An IP desk phone is a completely different type of device, it connects to your network via Ethernet and uses the SIP protocol to communicate with a business phone company. These two systems are not compatible. Plugging an IP phone into the NBN modem's phone port will not work, regardless of the phone model.

What is the difference between an IP phone and a cordless phone?

A cordless phone (such as a Panasonic or Uniden from JB Hi-Fi or Officeworks) is an analogue handset. It connects to an ATA adapter or the green port on your NBN modem and uses an analogue audio signal. An IP phone (such as a Yealink or Grandstream) connects to your router via Ethernet and communicates digitally using the SIP protocol with a business phone company. They are fundamentally different technologies. You cannot use a standard cordless phone as an IP phone without an ATA adapter.

My business phone company says they don't support my phone model. Can I still use it?

In most cases, yes. 'We don't support your phone model' from an AU business phone company typically means they do not offer auto-provisioning templates for that model, not that the phone is incompatible. SIP compliance improves interoperability but does not guarantee that every phone will work with every provider. Confirm the provider's authentication method, transport, codec, firmware and endpoint requirements before relying on manual configuration. You will just need to enter your SIP credentials manually via the phone's web interface rather than using auto-provisioning. If your provider insists the phone 'won't work', ask them to confirm whether the issue is auto-provisioning support or genuine SIP incompatibility. The latter is extremely rare with mainstream brands like Yealink and Grandstream.

How many simultaneous calls can I make on a standard NBN connection?

Each simultaneous call uses approximately 100kbps of bandwidth (G.711 codec, the standard Australian VOIP codec). At approximately 100 kbps per G.711 call, an NBN 25/5 connection has a pure theoretical upstream bandwidth capacity of about 50 simultaneous calls. Real capacity will be lower after allowing for other traffic, quality headroom, actual delivered speed and provider channel limits. On NBN 50 or above, bandwidth is rarely the limiting factor. Latency stability (low jitter) matters more than raw speed for call quality. If you need more than three or four simultaneous calls, use QoS settings on your router to prioritise VOIP traffic over other internet use.

Can I use an IP phone on Wi-Fi instead of Ethernet?

Wi-Fi support is model-specific. Some mid-range and high-end phones include it, some offer it only on a Wi-Fi variant or through an adapter, and others are Ethernet-only; check the exact model's specification. However, wired Ethernet always gives more stable call quality, lower latency, and more reliable registration than Wi-Fi. For reception desks, main business lines, or any phone where call reliability matters, use Ethernet. Wi-Fi is a reasonable option for meeting room or hot-desk phones where running a cable is not practical.

Every setup is different. Getting a Yealink registered on a 3CX system is different from registering it on a hosted cloud PBX like Maxotel. Tell us what phone you have, what system you're connecting to, and what error or status you're seeing. We reply personally. Not a bot, not a form letter.

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