For each concurrent call, you will need 90Kbps of both upload and download bandwidth capacity.
Note that this article only discusses concurrent calls, not users. Even if you have 100 users, if only 10 of them are on the phone at any one time then 10 concurrent calls of bandwidth capacity will be sufficient.
You can calculate how many concurrent calls your internet connection will support, simply by dividing it's lowest bandwidth direction (typically upload) by 90Kbps.
Capacity by connection type
Below is a table of maximum the maximum number of concurrent calls that can theoretically be made on each connection type, based on their theoretical maximum bandwidth capacities.
This should be used as a guide only, as actual speeds and capacity will vary depending on your location and provider. We recommend you Test Your Connection to see what your actual capacity is.
|Connection Type||Approx. Max Download||Approx. Max Upload||Max Concurrent Calls||Quality of Service (QoS)|
|1Gbps Fiber||1GBps||1GBps||10,000||Generally not required|
|100Mbps Fiber||100Mbps||100Mbps||1,000||Generally not required|
|40/40 EFM||40Mbps||40Mbps||400||Generally not required|
|20/20 EFM||20Mbps||20Mbps||200||Generally not required|
|10/10 EFM||10Mbps||10Mbps||100||Generally not required|
|NBN 100/40||100Mbps||40Mbps||400||Generally not required|
|NBN 50/20||50Mbps||20Mbps||200||Generally not required|
|NBN 25/10||25Mbps||10Mbps||100||Generally not required|
|NBN 25/5||25Mbps||5Mbps||50||Generally not required|
|NBN 12/1||12Mbps||1Mbps||10||Sometimes needed - See Quality of Service (QoS)|
|Typical||30-100Mbps||1Mbps||10||Sometimes needed - See Quality of Service (QoS)|
|Annex M||20Mbps||1.8Mbps||18||Generally not required|
|Standard||8Mbps||600Kbps||5||Recommended - See Quality of Service (QoS)|
|Telstra 4G/4GX||50-150Mps||5Mbps||50||Generally not required|
Testing your connection
In practice, the speed of your internet connection will vary by area. We recommend that you Test Your Connection to determine the actual capacity of your internet connection.
Quality of Service (QoS)
Quality of Service is a feature of most modern routers that priorities certain types of traffic over others.
For instance, if your VoIP service is sharing the same connection as other general internet usage, your a QoS capable router may prioritise your calls bandwidth requirements over other internet use.
Compressed Audio (G729)
Note that you may choose to use the G729 audio codec, which compresses audio and will provide approximately 3 times the channel capacity stated above.
However, we do not recommend doing so, as it significantly degrades audio quality.