DECT phone and answering machine - may need attention (Elmers End BR3)

BT DECT cordless phone system. Three handsets. One base station and two chargers. One-Tel DECT cordless phone and answering machine. Two hansets. One base station and one charger. These were previously in use as a single system with 5 handsets. However, they have been in a box (with the batteries removed) for 10 years. I can't get the old batteries to hold a charge and it will need new ones. (Size AAA, NiMh rechargeable - Amazon and others sell them). With new batteries fully charged, it may all work - but offered for someone who'd like to play.