Blank translation patterns are usually configured to setup Private Line Automatic Ringdown (PLAR) connections for the IP phones.
For more information, refer to Hotdial on IP Phones with CallManager Configuration Example.
However, creating null-to-null blank translation patterns accidentally on Cisco CallManager 3.0.11 and 3.1.2c makes all the phone fail.
Cisco bug ID CSCdv80764 has been resolved by disallowing the creation of null-to-null translation patterns.
The fix is applied to Cisco CallManager versions 3.1(3), 3.2, 3.3 and later.
Workaround: The blank translation pattern should be deleted or reconfigured with correct input parameters.