Internet Bandwidth for Asterisk VoIP Server , for Remote SIP user

Hello guys I put an Asterisk VoIP server for Telephony services purposes and have 500 remote SIP Users but don’t know how much internet bandwidth does the server required to handle 500 remote SIP users voice calls and based on what criteria will be counted the Internet bandwidth for SIP users , any one knows or have experience please share his/her thought with me,


The number of users is almost irrelevant - what matters is the number of
concurrent calls, and the codec/s you are using.

If you’re using G.711 (µ-law or A-law) a convenient rule of thumb is
100kbits/sec in each direction per call.

Any other codec will require less bandwidth.


I assume you mean as a SIP PABX for remote user agents. Asterisk will act as both client and server. (And the server hardware may need bandwidth for other reasons.)

This is not a function of the number of distinct user agents, but on the the maximum number of simultaneous calls.

One would typically budget on 100kbps, in both directions, for each call leg, so assuming half of your external user agents were making simultaneous calls to the remaining half, that’s about 50 Mb/s in both direction.

However this needs to be low latency, so you may need a safety margin.

The 100 kbps is a round number figure, based on the use of G.711 codecs.

Signalling and DNS traffic is normally much smaller.

Thank you for your quick answer , yes that is SIP PABX Server the client is using SIP Phones for voice telephony purposes with other SIP Client , my goal is only for Asterisk SIP PBX Server internet bandwidth .

the below codecs is using on my Asterisk PBX Server
allow = ulaw
allow = gsm
allow = alaw
allow = g723
allow = g729


thanks for your reply,

Assume 100 concurrent calls be at this case can I calculate 100kbit/s* 100 concurrent Calls = 9.76Mb , it mean 10Mbps Bandwidth is enough for 100 concurrent calls .


I made a mistake. There is no difference between conference and normal cases, both are 50Mbps for 250 calls.

With your 100 calls, you are talking about an absolute minimum of 20Mbps.

Also note that data rates are 1,000s, 1,000,000s, etc., not powers of two.

You need to leave some margin for signalling, DNS, etc. and I wouldn’t suggest going even close to the theoretical minimum without benchmarking.

G.729 and GSM will use less, but there is a high overhead, so you won’t get the full benefit.

G.729 and GSM are obsolete, as there are much better low bit rate codecs.

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