I have test lab with one router 1861 and four IP phone 7942 which are connected to switchport on router 1861.I have implemented with SCCP that time it was working fine but when I configured with SIP firmware cmterm-7942_7962-sip.8-5-3SR1.zip , all phones are automatically rebooting continously.
I have attached details about configuration of 1861 and flash output.
It would be greatful to get the correct solution.
Based on this link:
Note For all SIP firmware upgrades from firmware release versions earlier than 8.3(3) to version 8.5(3) or greater, you must first upgrade your firmware to version 8.5(2). Once you have upgraded to version 8.5(2), you can upgrade your IP Phone to version 8.5(3) or later.