9971 call preservation failure

[heathrw]

I'm running Call manager 8.5(1) with Cisco 9971 IP Phones running firmware 9.1.1(SR1)
When a 9971 is in an active conversation with a same type phone or a SCCP 7975 call Preservation does not work.

How ever calls are preserved with two SCCP 7975 phones.

Thanks

[dijohn]

Can you get a packet capture from the SIP Phone 9971?

You should see something like this.. Which side is going into Call Preserve state? Is it the 9971 or the 7975 with the loss of connectivity.!?

NOTIFY 
sip:47b99e84-71eb-4617-ae59-15a2ab451712@14.50.211.198:49603;transport=TCP 
SIP/2.0
Via: SIP/2.0/TCP 14.50.211.80:5060;branch=z9hG4bK1949e42157
From: 
<4>;tag=1c44a18a-faba-49c0-81ff-ddea413ef792-33551751
To: "5290" <5290>;tag=fcfbfb10fd4900043a5af12a-536074ec
Call-ID:  <mailto:fcfbfb10-fd490003-4b5626aa-679dbffd@14.50.211.198> 
fcfbfb10-fd490003-4b5626aa-679dbffd@14.50.211.198
CSeq: 102 NOTIFY
Max-Forwards: 70
Date: Fri, 10 Dec 2010 17:06:42 GMT
User-Agent: Cisco-CUCM8.0
Event: service-control
Subscription-State: active
Contact: <14.50.211.80:5060>
Content-Type: text/plain
Content-Length: 94

action=call-preservation
<mailto:RegisterCallId={fcfbfb10-fd490002-169f385e-185f2afc@14.50.211.198> 
RegisterCallId={fcfbfb10-fd490002-169f385e-185f2afc@14.50.211.198} 

Regards,
Divin