Model 26958GE1-A 900 MHz. I've had this phone for at least seven years. Recently, at exactly 60 minutes of talk time on the cordless hand held, the call disconnects. I hear "beep beep beep" and I have to hang up and redial the number. I replaced the battery and fully charged it but the problem is still happening. The person on the other end gets no warning before the call is disconnected. Why is this happening?