We do have stock of the BT Advanced main base unit which is fully compatible with Advanced Z handsets!

BT Advanced Z main base only - for use with a BT Advanced Z & Advanced handsets only. Up to 5 additional handsets (6 including the main handset) can be added to this system, giving the user the option to expand. 

Does not include power supply (sold separately). The main base is the central communication for all the handsets, if your main base station is faulty none of your handsets will work, making this an ideal replacement for faulty main base stations.