Will VoIP over BRI in backup mode work when the T1 fails?

[admin_2]

Scenario: (2) 3640's each with (1)T1 to PBX for VoIP ( 8 channels of T1 using G.729). The 3640's are connected on the WAN using a Single T1 using either PPP or Frame. A single BRI is used for dial back. Question: Will VoIP over BRI in backup mode work. Will at least a few voice calls work?

[#2]

Yes a few calls would work but you have to ensure the right QOS is in place. LLq and LFI. Also under the voip dial-peer, you might want to limit the number of acceptable calls so that we dont oversubscribe the isdn 128kb link.

g729 = 26Kb/s for one voice call with no crtp

i.e you can only have 75% of 128/26 calls for good quality to

be achived =3 calls.

If doing crtp then one voice call now uses 12KB/s and you can have

8 calls.

The command to use to limit accepted call under dial-peer

is " max-conn "