Issue: Acme Packet SBC sending duplicate SIP attributes which causes MS Lync 2013 to drop the call. However, Cisco CUBE and Cisco Voice Gateways have no problem in processing duplicate attributes.
o=- 1385372910 1385372910 IN IP4 192.168.1.1
c=IN IP4 192.168.1.1
m=audio 10178 RTP/AVP 0 8 101
a=silenceSupp:off – – – –
Platform: Acme Packet Net-Net 3800 with software version SCX 6.3.7
Solution: Use HMR to remove all attributes and re-add attributes with single entry before sending to MS Lync 2013.
Acme Packet acknowledged this as a bug in the code. The patch has been released on 4th of December 2013 and available on Acme Packet Support page for download.