A bit more detail wouldn't hurt but at a guess you have your landline diverted to your mobile so effectively you are ringing your own mobile each time you try
Thanks - when I use my BT mobile to phone our BT landline, the home phone rings but as soon as it's picked up the line goes dead. At the mobile end , you don't even hear a ringing tone and the call ends. My wife's phone is with Lebara (Vodafone network I think) and has no problem. Also my BT mobile has no problem calling other landlines. I'll check out if it is on call divert but I've never used or requested a call divert.