CUBE & OCS Interrop

Unanswered Question
Mar 23rd, 2012
User Badges:
  • Blue, 1500 points or more

I'm having a problem with CUBE (152-1.T) & Microsoft OCS:

For national calls, the SIP call sets up fine. For international calls, as soon as the user has finished dialling, OCS gives an N/U.

Looking at the SIP messages, the main difference is that for National calls, we get a SIP INVITE, and then send a SIP TRYING, followed by a SIP RINGING.

But for International calls, we get a SIP INVITE, send a SIP TRYING, then fairly quickly afterwards, we send a SIP 183 Session Progress. After that, everything goes quiet. We get nothing from OCS, and we send OCS nothing.

I'm guessing that OCS is chocking on the 183 Session Progress.

Thoughts or suggestions ?


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
acampbell Fri, 03/23/2012 - 09:56
User Badges:
  • Green, 3000 points or more


From the interoperability portal link

Early-media negotiation may not be supported due to the new provisional response mechanism implemented on Microsoft

OCS 2007 R2. Microsoft OCS 2007 R2 sends three provisional responses to a single INVITE (183 w/SDP, 180, 183)

which causes incompatibility agaianst Cisco UBE which expects ringback media to flow from the Miscrosoft OCS due to

the 183 with SDP response message (early media indication), but the Microsoft OCS does not send ringback media and

the calling user never hears ringback. The workaround is to use the command “

voice-class sip block 183 sdp present”

and apply it to the appropriate dial-peer, not globally, in Cisco UBE to block all 183 messages from msft OCS toward

Cisco UCM allowing only 180 message to be sent to Cisco UCM and receiving local generated ringback on the calling


Not sure if this is relevant




This Discussion

Related Content