Voice2: Voice unit keeps dropping the line and locking up

Voice2 units keep dropping line and locking up. 
Customer was advised to change the following Voice2 unit settings
a) change disconnect timer from 40 sec to 3-7 seconds on both server and client 
b) change the codec to a Speex either 34.2 or 42.2 (these offer similar performance to G722 but are more resilient to errors on the line ) 
c) make sure the trace level on both server and client is set back to 1 
d) make sure jitter buffers are set between 200ms - 500ms 
This resulted in the units not locking up 
Note: See other solutions on Voice2 unit