Microsoft has released two hotfixes for Lync Server 2010.
KB2670430
This one fixes this issue:
2658817 Calls do not always connect if you have a DNS balancer and multi-homed network deployed in a Lync Server 2010 environment
Read about it here
Get it from Microsoft PSS if you have the problem, or wait for the next cumulative update to Lync.
KB2665325
This one fixes this issue:
2670434 A user cannot sign in by using a mobile device in a Lync Server 2010 environment that has Mobility Service deployed
Read about it here
Get it from Microsoft PSS if you have the problem, or wait for the next cumulative update to Lync.
cool!