Calculating VoIP Bandwidth And Data Allowance

How fast does my internet connection need to be?

Data connections have two components – bandwidth and data allowance.

• Bandwidth is measured in MegaBITS per second (Mbps) – 1024 Kilobits = 1 Megabit
• Download allowance is measured in MegaBYTES (MB) – 1024 Kilobytes = 1 Megabyte

How much data would be used based on 1-hour audio call using the G711 or G722 codecs with allowance for an IPv6 overhead?

• Each Phone, when in use, requires 80-100Kbps(down)/80-100Kbps(up) per voice call.
• Each phone, when in use, will use 38 MB of your data allowance per hour.

Example: An ADSL Connection (Asymmetric Digital Subscriber Line) may have connection speeds of 3.2Mbps/.8Mbps. Therefore, the available bandwidth at any one time is 3.2Mb for download, and .8Mb for upload.

Calculating Download Capacity of the above example:

Formula: (No. of Mbps * 10) = Possible number of concurrent calls over available download bandwidth.

3.2* 10 = 32

Calculating the Upload Capacity of the above example:

Formula: (No. of Mbps * 10 = Possible number of concurrent calls over available upload bandwidth.

.8 * 10 = 8

Therefore, because the most calls possible on the existing upload capacity is 8, only 8 phones should be used on this data connection.
If the 8 phones were in use for 10 hours each, the total amount of data allowance used would be:

8 * 10 * 38MB = 3040MB

To summarise, an ADSL Connection with speeds of 3.2Mbps/.8Mbps will support 8 phones, and use 3040MB of data over 80 hours of talk time with NO Available bandwidth left for anything else.