May of us are experiencing a few problems after upgrading 8941/8945 phones to firmware version 9-3-1 such as SCCP phones cannot access the corporate directory. Pressing the directories button does nothing. Other phone services and functions which are dependent on the phone receiving it's TFTP configuration file may not work. On the other hand SIP phones may not even register to CUCM after an upgrade to 9-3-1. In both of these cases downgrading the phone's firmware fixes all these issues.
The reason and solution is documented in the 8941/8945 release notes for 9-3-1. The latest device pack must be installed which requires a reboot for these phones to function properly on the 9-3-1 firmware.
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Note
The Cisco IP Phone 8941 and 8945 support a new "secure by default" feature with this release. Before phones are upgraded to Firmware Release 9.3(1), the Cisco Unified Communications Manager must have devpack 8.0.3(24049)/8.5.1(14070)/8.6.2(22030) or higher installed. The phones require this devpack. If the correct devpack is not installed first, the phones cannot successfully register to the Cisco Unified Communications Manager.
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http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/8941_8945/firmware/9_3_1/release_notes/P415_BK_R3969224_00_rn-9_3_1-8941-8945_chapter_00.html#P415_TP_I0D9096E_00
