Was trying to connect a Polycom VVX Expansion Module with a ADTRAN VVX400 phone set. Added the module (1) and selected the type (LCD), then connected the AUX cable between the devices, the phone rebooted, the expansion module LED lights lite up, but then nothing.
Is there a compatibility issue ADTRAN VVX phones and the Polycom Expansion Module??m
Were you using the LCD or Paper Expansion Module? I can't find any reference from ADTRAN about the LCD being compatible.