Verify if the 11xx and 12xx series IP phones can register to TPS. If the phones cannot register to TPS, do any of the following:
Examine the dsa.log file for server connection problems.
Ensure that the Session Manager identity certificates key length is at least 2048 bit.
If mutual DTLS authentication is enabled, ensure that the Client Identity Certificate that is installed on the phone has a key length of at least 2048 bit.
