7100i Ring Problem (by 2 users)

I'm using the Nextel 7100i. Somehow I have done something wrong and when I get a phone call I get not only the ringtone I set it on but also a regular phone ring as well. Even worse--if I set it on quiet, vibrate, or even off, phone calls still ring through with the regular ring (as opposed to ringtone). All settings appear to be right--e.g., mute on quiet, etc.

Help please?!!