We have Lync 2013 and 2010 in our topology with Cisco Call Manager version 8.x. Simultaneous ring worked for a while but is no longer fully functional. Lync client to Lync client calls ring in Lync and on the desktop phone but calls to the desk number do not ring in Lync. Users are set up in mobility and set for enterprise voice and have a URI. The voice policy has sim ring enabled. I don't see much in the logs but I might be looking in the wrong place. Anywhere I can look on the log server or client side to narrow it down? I am not the VoIP guy but any help would be appreciated.

The questions confused me a bit.  I have a few questions to clarify if you don't mind:

When you say the desk number, is that a Lync or Cisco number? 

Is the desktop phone a Cisco phone or Lync phone? 

Are you using Cisco mobility to simultaneously ring Lync, or are you referring to Lync mobility?

Do you get an error, a funny tone, or does nothing happen?

I'd run the logger on the front end server/pool and watch sipstack.  You should be able to search for phone number and see if you see an

Setup simultaneous ring

1. From the My Info screen tap Simultaneously Ring or Call Forwarding.
2. On the Call Forwarding screen, tap Simultaneously Ring, and select the following:

• Tap New Number and type in a new phone number.
• Tap and select a number youve added before, such as your mobile phone.

3. Under Apply settings during these hours select when this setting should apply.
4. Tap Done to save your change

Also you can refer below link

http://office.microsoft.com/en-001/lync-help/call-forward-and-simultaneously-ring-HA103700756.as

Check the following document about how to configure simultaneous ring feature between Lync Server and Cisco Unified Communications Manager:

http://www.cisco.com/en/US/solutions/collateral/ns340/ns414/ns728/ns784/1048876.pdf

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