Inbound PSTN - Forward PSTN - No Way Audio

Unanswered Question
Feb 26th, 2009

Here's a description, and I'll try to be brief.


Call Manager 4.1

2821 router

T1 (2 port) Multi-Flex Trunk WAN daughter card


We're finding that inbound calls from the PSTN that are forwarded back out to the PSTN will generate a ring for the called number, they answer, no audio. On the calling end, they hear ring no answer.


So, I believe this will be a problem with the T1 in question, but I don't know what the problem is.


Also of note... forwarding internally and externally from inside works. So it's only a hairpin call that triggers condition.


The following is some of the configuration involved for this card.


no network-clock-participate wic 3


controller T1 0/3/0

framing esf

clock source internal

linecode b8zs

channel-group 0 timeslots 1-24

controller T1 0/3/1

framing esf

linecode b8zs

channel-group 0 timeslots 1-24



interface Serial0/3/0:0

no ip address

encapsulation ppp

ppp multilink

ppp multilink group 1

!

interface Serial0/3/1:0

no ip address

encapsulation ppp

ppp multilink

ppp multilink group 1


The interface is reporting errors.


Thanks for any feedback!

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Nicholas Matthews Thu, 02/26/2009 - 13:08

You can try this command:


voice-card 0

no local-bypass



I don't suspect that it will fix the problem, but it is worth a try. What type of errors are you getting?


The PPP link is not a voice circuit, so if calls are going out of that link they aren't really 'hairpinned', and it's most likely a routing/firewall issue.



Clarification would help.



-nick

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