[asterisk-users] cisco 7940 and asterisk 11

Julian Lyndon-Smith asterisk at dotr.com
Tue Feb 12 08:29:15 CST 2013

Ever since we upgraded to asterisk 11 we have had audio problems with
our cisco 7940 phones.

The problems manifest themselves by the conversation turning "robotic"
or into silence (to the extent our agents are saying "hello? hello?"
and the customer is saying "I hear you just fine"

We had to change pedantic=no in sip.conf to allow the phones to register

We are assuming that it is the phone<=>asterisk combination because

a) the call recordings of the conversation are perfect (no noise on
the line, conversation is clear) but it is apparent that the agent
cannot hear the customer sometimes (Hello?)

b) we have replaced the cables and switches between the phones and the pbx

c) we don't have the same problem with Aastra 9133i or Polycom 331 phones

Are there any settings in sip.conf that may help this , or a
particular firmware ? Are there any known audio problems with cisco
7940 and asterisk 11 ?

Many thanks


Julian Lyndon-Smith
IT Director, Dot R Limited

"I don’t care if it works on your machine!  We are not shipping your machine!”

The kangaroo dances: http://www.youtube.com/watch?v=MAWl5iYOaUg

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