Call hold vs. media bypass in CUCM-Lync infrastructure

Question

Dear Colleagues,
We have built a heterogeneous UC infrastructure based on Lync Server 2013 and CUCM 9.1.2.11900-12 and we experienced, that with media bypass, we cant hold the calls on Lync side. I checked the SIP logs on both sides and I saw, when Lync sends a re-invite, CUCM responds with 200 OK and in this there is a parameter "b=CT:64" and unfortunately the Lync could not handle it.
After some investigation I found this link: http://johnacook.wordpress.com/2014/03/27/the-case-of-the-curious-sdp-with-lync-call-manager-media-bypass-and-call-hold-and-resume/
In the post, the author mentioned a LUA script:
M = {} function M.outbound_ANY(msg) local sdp = msg:getSdp() if sdp then local b_CT_line = sdp:getLine(“b=CT”,”64″) if b_CT_line then b_CT_line = b_CT_line:gsub(“64″, “1000”) sdp = sdp:modifyLine(“b=CT”, “64”, b_CT_line) msg:setSdp(sdp) end end end function M.outbound_ANY_ANY(msg) local sdp = msg:getSdp() if sdp then local b_CT_line = sdp:getLine(“b=CT”,”64″) if b_CT_line then b_CT_line = b_CT_line:gsub(“64″, “1000”) sdp = sdp:modifyLine(“b=CT”, “64”, b_CT_line) msg:setSdp(sdp) end end end
return M
I have created a SIP normalization script and afterwards I have assigned it to the SIP trunk but unfortunately the problem still exists.
Do I have to do anything else? Did I miss something?
Thanks,
Laci

Answer 1

Hello Laci, did you fix this issue? 
We have similar setup and while testing the media bypass, we faced the issue with call hold and hence decided to upgrade the lync client for all the users. 
Wanted to check if you have any other solution for this call hold issue.