AT&T EP5962 Phone "t20 pd" Questions

I have the AT&T Model EP 5962 and the cordless is giving me error message T20 PD. How do I resolve this? Thank you. Contact with AT

...T20 PD. How do I correct this and make the base find the handselt? I tried the solution Crystalina_c gave and it didn't work for me. It seemed the battery was loose or not as snug and had some wiggle ...