I turned on Lync client logging, and got the following interesting info, which finally says "No MCU Factory Available" - what the heck is the MCU factory?
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A SIP request made by Communicator failed in an unexpected manner (status code 80ef025b). More information is contained in the following technical data:
RequestUri: sip:Peter.Moreton@acme.org.uk;gruu;opaque=app:conf:audio-video:id:R144Q0W1
From: sip:peter.moreton@acme.org.uk;tag=84f848a6bf
To: sip:Peter.Moreton@acme.org.uk;gruu;opaque=app:conf:audio-video:id:R144Q0W1;tag=EB2CB0D8F3501021BF64C1175CC967BE
Call-ID: dc21fe48c73147c786e6205f1f34c552
Content-type: multipart/alternative;boundary="----=_NextPart_000_1C2F_01CC0B05.F9F189C0";call-type=audiovideo
------=_NextPart_000_1C2F_01CC0B05.F9F189C0
Content-Type: application/sdp
Content-Transfer-Encoding: 7bit
Content-ID: <b236f6cbe2eb4dedba8648fcb00ea6b7@acme.org.uk>
Content-Disposition: session; handling=optional; ms-proxy-2007fallback
v=0
o=- 0 0 IN IP4 172.23.136.22
s=session
c=IN IP4 172.23.136.22
b=CT:99980
t=0 0
m=audio 10238 RTP/AVP 114 9 112 111 0 8 116 115 4 97 13 118 101
a=candidate:DpPgwRYqpEsMSRXkcL0CI3E8bZFt/MR9LYesTZes7pE 1 +PF7yT2Rs4b4M/UvvjIEMA UDP 0.830 192.168.56.1 21526
a=candidate:DpPgwRYqpEsMSRXkcL0CI3E8bZFt/MR9LYesTZes7pE 2 +PF7yT2Rs4b4M/UvvjIEMA UDP 0.830 192.168.56.1 21527
a=candidate:CWVrvOij1l0zVer+GSvVjFL+85gIi1ytZH8xhgSb38U 1 HISDkpq4/8HkJ4DuDoh7rw UDP 0.840 192.168.139.1 19292
a=candidate:CWVrvOij1l0zVer+GSvVjFL+85gIi1ytZH8xhgSb38U 2 HISDkpq4/8HkJ4DuDoh7rw UDP 0.840 192.168.139.1 19293
a=candidate:PEiTWe3vsRzz37MXmw8GIZnKqDmPhq4xvBsTN/LhRwk 1 klhngYPWlITM/OreS/38WQ UDP 0.850 192.168.91.1 29730
a=candidate:PEiTWe3vsRzz37MXmw8GIZnKqDmPhq4xvBsTN/LhRwk 2 klhngYPWlITM/OreS/38WQ UDP 0.850 192.168.91.1 29731
a=candidate:9m768FBc5MmcgNmCtp+qnvmYw1hF5FacsQjZznOPPC8 1 nKCbhJMxpazcs2JXxjChTQ UDP 0.860 172.23.136.22 10238
a=candidate:9m768FBc5MmcgNmCtp+qnvmYw1hF5FacsQjZznOPPC8 2 nKCbhJMxpazcs2JXxjChTQ UDP 0.860 172.23.136.22 10239
a=candidate:sdNSHY58DMbyFJX9qpOszKURZ0ujaY22uufwq9yo0WY 1 XPQ4PdumH/44Ze6FLIo/eg TCP 0.190 85.118.19.29 53118
a=candidate:sdNSHY58DMbyFJX9qpOszKURZ0ujaY22uufwq9yo0WY 2 XPQ4PdumH/44Ze6FLIo/eg TCP 0.190 85.118.19.29 53118
a=candidate:mYpqLAf+7vVW0qVNTQIn5kutVtxMCP/KESuGl/iMU3k 1 AW68x+qOHHVR8T5yJKt7Nw UDP 0.490 85.118.19.29 57676
a=candidate:mYpqLAf+7vVW0qVNTQIn5kutVtxMCP/KESuGl/iMU3k 2 AW68x+qOHHVR8T5yJKt7Nw UDP 0.490 85.118.19.29 56794
a=candidate:TwiWJFXQjLberrxWBj93Um5Yi0hK6ood52qEhJZi2W4 1 v4m4e1nsUxlG61iKYB8aEA TCP 0.250 172.23.136.22 29527
a=candidate:TwiWJFXQjLberrxWBj93Um5Yi0hK6ood52qEhJZi2W4 2 v4m4e1nsUxlG61iKYB8aEA TCP 0.250 172.23.136.22 29527
a=cryptoscale:1 client AES_CM_128_HMAC_SHA1_80 inline:7S9LTx8PnauAPlJ3g5Fykt28aZ6Akz4YbxbOmaUE|2^31|1:1
a=crypto:2 AES_CM_128_HMAC_SHA1_80 inline:/0zyG/nmzgRkhPxWIKVAmdOrcPchr+9pKyEU5MpM|2^31|1:1
a=crypto:3 AES_CM_128_HMAC_SHA1_80 inline:cKvO64LLVQGrwlTI4D+hJz8nZ+geipIaI/XsDin5|2^31
a=maxptime:200
a=rtpmap:114 x-msrta/16000
a=fmtp:114 bitrate=29000
a=rtpmap:9 G722/8000
a=rtpmap:112 G7221/16000
a=fmtp:112 bitrate=24000
a=rtpmap:111 SIREN/16000
a=fmtp:111 bitrate=16000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:116 AAL2-G726-32/8000
a=rtpmap:115 x-msrta/8000
a=fmtp:115 bitrate=11800
a=rtpmap:4 G723/8000
a=rtpmap:97 RED/8000
a=rtpmap:13 CN/8000
a=rtpmap:118 CN/16000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=encryption:optional
------=_NextPart_000_1C2F_01CC0B05.F9F189C0
Content-Type: application/sdp
Content-Transfer-Encoding: 7bit
Content-ID: <afd6e1f33a9c4ad485bb9a55cc1bf467@acme.org.uk>
Content-Disposition: session; handling=optional
v=0
o=- 0 0 IN IP4 172.23.136.22
s=session
c=IN IP4 172.23.136.22
b=CT:99980
t=0 0
m=audio 16452 RTP/AVP 114 9 112 111 0 8 116 115 4 97 13 118 101
a=ice-ufrag:rORg
a=ice-pwd:YN97WrBINeFDgv5fqWfNCK/L
a=candidate:1 1 UDP 2130706431 172.23.136.22 16452 typ host
a=candidate:1 2 UDP 2130705918 172.23.136.22 16453 typ host
a=candidate:2 1 UDP 2130705919 192.168.91.1 18918 typ host
a=candidate:2 2 UDP 2130705406 192.168.91.1 18919 typ host
a=candidate:3 1 UDP 2130705407 192.168.139.1 12322 typ host
a=candidate:3 2 UDP 2130704894 192.168.139.1 12323 typ host
a=candidate:4 1 UDP 2130704895 192.168.56.1 12270 typ host
a=candidate:4 2 UDP 2130704382 192.168.56.1 12271 typ host
a=candidate:5 1 TCP-PASS 6556159 85.118.19.29 56355 typ relay raddr 172.23.136.22 rport 32497
a=candidate:5 2 TCP-PASS 6556158 85.118.19.29 56355 typ relay raddr 172.23.136.22 rport 32497
a=candidate:6 1 UDP 16648703 85.118.19.29 55359 typ relay raddr 172.23.136.22 rport 3444
a=candidate:6 2 UDP 16648702 85.118.19.29 57390 typ relay raddr 172.23.136.22 rport 3445
a=candidate:7 1 TCP-ACT 7075327 85.118.19.29 56355 typ relay raddr 172.23.136.22 rport 32497
a=candidate:7 2 TCP-ACT 7074814 85.118.19.29 56355 typ relay raddr 172.23.136.22 rport 32497
a=candidate:8 1 TCP-ACT 1684796415 172.23.136.22 32497 typ srflx raddr 172.23.136.22 rport 32497
a=candidate:8 2 TCP-ACT 1684795902 172.23.136.22 32497 typ srflx raddr 172.23.136.22 rport 32497
a=cryptoscale:1 client AES_CM_128_HMAC_SHA1_80 inline:7S9LTx8PnauAPlJ3g5Fykt28aZ6Akz4YbxbOmaUE|2^31|1:1
a=crypto:2 AES_CM_128_HMAC_SHA1_80 inline:/0zyG/nmzgRkhPxWIKVAmdOrcPchr+9pKyEU5MpM|2^31|1:1
a=crypto:3 AES_CM_128_HMAC_SHA1_80 inline:cKvO64LLVQGrwlTI4D+hJz8nZ+geipIaI/XsDin5|2^31
a=maxptime:200
a=rtpmap:114 x-msrta/16000
a=fmtp:114 bitrate=29000
a=rtpmap:9 G722/8000
a=rtpmap:112 G7221/16000
a=fmtp:112 bitrate=24000
a=rtpmap:111 SIREN/16000
a=fmtp:111 bitrate=16000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:116 AAL2-G726-32/8000
a=rtpmap:115 x-msrta/8000
a=fmtp:115 bitrate=11800
a=rtpmap:4 G723/8000
a=rtpmap:97 RED/8000
a=rtpmap:13 CN/8000
a=rtpmap:118 CN/16000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=encryption:optional
------=_NextPart_000_1C2F_01CC0B05.F9F189C0--
Response Data:
603 Decline
ms-diagnostics: 3098;reason="No MCU Factory Available";source="SRVCENLYN01.acme.org.uk";OriginalPresenceState="0";CurrentPresenceState="0";MeInsideUser="Yes";ConversationInitiatedBy="0";SourceNetwork="0";RemotePartyCanDoIM="No"
Resolution:
If this error continues to occur, please contact your network administrator. The network administrator can use a tool like winerror.exe from the Windows Resource Kit or lcserror.exe from the Office Communications Server Resource Kit in order to interpret
any error codes listed above.