It depends upon what you mean by "wanders a lot" and specifically the distance involved. A retail cordless phone is connected to the same base station all the time so will fade the further you are away from that base station.
Companion was discontinued circa 2000. If you are based in Canada, you MAY be able to buy the components on ebay,... If you are based in the US, you are SOL since UTAM activation codes are no longer available. If you are based outside of US/Canada, there are DECT-based solutions.