The one-way call issue due to wrong peer address in AR1200

Publication Date:  2014-06-26 Views:  440 Downloads:  0
Issue Description
A customer configured an AR to connect to IMS network using SIP AT0 trunk. After he finished the configuration, the SIP AT0 trunk can register to IMS network, and he can make the outgoing call, but there was a one-way call issue. He can hear the voice from other end, but the other end can’t hear his voice.
This is the topology:

In the topology, if the customer called from the phone 901454 connecting to AR to the remote phone 232505, he can hear the voice from other end, but the other end can’t hear his voice. In the same office there are two line connect to IMS network, if called from other phone 232508 to the remote end 232505, the call worked all right, and there was no issue.

The related configuration in AR1200:
voice
voip-address media interface GigabitEthernet 0/0/0.30 172.16.27.2
voip-address signalling interface GigabitEthernet 0/0/0.30 172.16.27.2
area-code 92 901
pbx default-country-code 92 default-area-code 901
#
trunk-group sip sip trunk-circuit
  signalling-address ip 172.16.27.2 port 5060
  media-ip 172.16.27.2
  peer-address static 10.8.19.66 5060
  register-uri  fwoxx.com
  home-domain  fwoxx.com
  number-parameter 7 1
  number-parameter 19 1
  number-parameter 42 0
  trunk-sipat0 +92901454 default-called-telno 454 caller-telno 454
  trunk-sipat0 +92901454 password cipher  xxx
#
callprefix test_in //for incoming call
  prefix 4
  call-type category basic-service attribute 0
  digit-length 1 3
#
callprefix 2 //for outgoing call
  prefix 2
  call-type category basic-service attribute 0
  digit-length 1 20
  destination-location inter-office
  callroute trunkgroup1 sip
#
pbxuser 454 pots  //the phone user
  port 2/0/2
  telno 454
  call-right in international-toll out international-toll
  service-right call-intercept disable
#
Alarm Information
None
Handling Process
(1) Checked the configuration of AR, since the outgoing call started working, so the outgoing call configuration is OK.
(2) Captured packet in the outgoing call, we can see that the AR had sent the voice from local, but we didn’t know why the other end couldn’t hear it.
The steps are as follows:
(2.1) Open the captured packet, select “VOIP Calls” in the following picture:

(2.2) Select the only one call message, and click “Player” button.

(2.3) click “Decode ” button :

(2.4) Select the voice stream from local (172.16.27.2) to the remote end(172.16.10.36), then click “Play” button:

Here we can see that the AR had sent the voice from local to the remote end.
(3) In the before test, the local phone (232508 ) was used another line which was different from the one AR connected. Try to replace the AR with a Phone in the same line, then connected this phone to IMS network directly. In this situation, this Phone would have this number 901454, and the outgoing call worked all right, both end could hear each other.
Compare the captured packet, we found that this Phone registered on the IP 10.8.19.97.

But when the one-way call issue happened, the AR registered on the IP 10.8.19.66, which is different from 10.8.19.97 when the both call worked all right.

Solution:
In the configuration for AR:
trunk-group sip sip trunk-circuit
  signalling-address ip 172.16.27.2 port 5060
  media-ip 172.16.27.2
  peer-address static 10.8.19.66 5060  //--change the peer-address to 10.8.19.97
  register-uri fwoxx.com
  home-domain fwoxx.com
After the change, the outgoing call worked all right when the Phone connected to AR which registered to IMS network.
Root Cause
1) The outing configuration is not correct.
2) The peer address is not correct.
Suggestions
When deploy AR voice function, you should ask the customer to provide the right parameter. If unfortunately the customer provides the wrong parameter, you can use other devices which work fine and capture packets to conclude the right parameter.
In troubleshooting for AR voice feature, it’s very useful to get the debug information and capture the packets.

END