Nortel Companion MICS-XC Installation Manual page 11

Norstar Companion basics / 5
Note: Versions 4.0 and 5.0 are also supported.
For information on how to access Norstar Voice Mail using
your Norstar Companion portable, refer to the Portable
Telephone Feature Card that is supplied with it.
P0881594 Issue 01 MICS-XC Norstar-Companion Installer Guide