After an Avaya Aura® Communication Manager (CM) upgrade, a customer called Avaya support because their SIP telephones were unable to login. Support was able to confirm that the telephones had not been upgraded.

Which pre-implementation step was omitted?

A. Provide accurate licensing specification.

B. Verify version installed is compatible with existing versions.

C. Test all third-party equipment and software.
D. Access support.avaya.com to verify customer systems compatibility.