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incoming call failed with 400 Bad Request

Publication Date:  2017-11-30 Views:  411 Downloads:  0
Issue Description

if configure display name from softswitch ,incoming call failed with 400 bad message, after remove the display name in softswitch ,everything works fine

network topology as bellow.

Handling Process

1. check current configuration , confirm configuration no problem .
2. capture the signaling logs , trace signaling find any fault in the messages
 from MDU can use open dbwin to trace the signaling logs : dbwin to trace the signaling
  MA5620E(su)%%dbwin enable
  MA5620E(su)%%dbwin print 0x9d 1 1
  MA5620E(su)%%dbwin send 0x9d 1 1

  2.reappear this issue ,you will see the signaling print out , please feedback the signaling trace log .
  after log collect ,close the dbwin .

  MA5620E(su)%%dbwin print 0x9d 1 0
  MA5620E(su)%%dbwin send 0x9d 1 0
  MA5620E(su)%%dbwin disable

Root Cause

Analysis the SIP signaling of the incoming call, we found that the MA5620 reply an error message (SIP/2.0 400 Bad Request) when received the INVITE message. There is a warning in the reply that is “Warning: 399 "SS150000F150L1936[05406] P-Asserted-ID usage error"”:

Then we checked the P-Asserted-ID in the INVITE message and found that there were two same URI(<sip:3640@>) in the P-Asserted-Identity header, this is why MA5620 reply 400 Bad Request to the INVITE message:

MA5620 do this checking base on this description in the RFC3325:
If there are two values, one value MUST be a sip or sips URI and the other MUST be a tel URI


1.suggest remove the duplicate URI form softswitch

2.version V800R312C00SPH226 will optimize it according RFC 5876 ,to ignore the duplicate URI.


1.trace the signaling is the common method when we do VOIP troubleshooting ;

2.suggest customer when configure VOIP service in softswitch according the standard and consider old device can support it .

3.reference RFC document :