NTLsx701 base conection. hi. the battery in my handset went dead. so the missis decided to try

Question

hi. the battery in my handset went dead. so the missis decided to try swapping them.now the phone has power but is saying no base on the screen. i no i have to match them as when i first baught them.but sinse then weev had a house move and lost the manual. any help would be great thanksmarkmy d4000 wont find the base after i left it boxed up for a while