If your business is setting up a VOIP phone system (phone calls made over your internet connection, instead of the copper phone line) and you are not sure how many lines, channels, or extensions you actually need, this calculator works it out for you. Most businesses over-order lines and under-order extensions because the terminology is confusing. Enter your team size and peak call behaviour and we will give you the exact numbers to put in your quote request.
Not sure how many phone lines your business actually needs, or confused about the difference between lines, channels, and extensions? Tell us your team size and how many calls you typically handle at once.
Ask us directly →Include anyone who makes or receives business calls.
Not sure? A rough rule: about 30-50% of phone-using staff at any given busy moment.
Suggested estimate: 2 (40% of your team)
You need a VOIP plan that supports at least 2 simultaneous calls.
You need 1 phone number (1 main number).
Each staff member gets an extension regardless of whether they have their own phone number.
Based on typical AU hosted VOIP pricing for 2 channels / 5 users
These figures are the recommended starting point. Your provider will confirm final line counts during setup. If your result seems too high or too low for your situation, tell us your setup and we will check it →
Get a free quote for 5 usersA channel (sometimes called a "line" or "trunk") is a path for one phone call. If you need 5 people on calls at the same time, you need 5 channels. Most VOIP plans include enough channels for your team size automatically.
A phone number is what people dial to reach you. You might have one main number (02 XXXX XXXX) or one per staff member.
An extension is an internal shortcode (like 101, 102) that lets staff transfer calls to each other. Every staff member gets one. These do not cost extra.
In VOIP, they mean the same thing. One channel = one simultaneous call. Old landline terminology used "lines", VOIP providers usually say "channels" or "concurrent calls."
No. You only need enough channels for the maximum number of simultaneous calls. In a 10-person office, you rarely have more than 4-5 people on calls at once. This is why the calculator asks about your peak concurrent usage rather than your total staff count.
With most AU VOIP providers, additional numbers (DIDs) cost $3-10/month each. A main number is typically included in your plan. 1300 and 1800 numbers are more expensive, $10-30/month for 1300 and $15-50/month for 1800, and also attract per-minute charges on top.
Yes. Hosted VOIP scales instantly. Adding a new user or channel is usually a same-day change in your provider's portal. There is no need to over-provision at the start, start with what you need and add capacity as your team grows.
If you still receive faxes, yes, a dedicated fax number routed to a fax-to-email service is the modern approach. You receive the fax as a PDF in your inbox, no fax machine required. This typically costs around $5-10/month for the number plus the fax-to-email service.
Maxotel can scope your requirements in a 10-minute call, no obligation, no sales pressure. They specialise in Australian SMBs with exactly this size team.
Get a free quote for 5 usersRelated tools: Phone Bill Translator | Phone System Sizing Wizard