rings every day dont get time to answer it and they have hung up when i try ringing back it is always engaged

Numerous calls since 7 Sep 12 with no one on end of call when picking up. Probably computer initiated. Caller ID shows this basic format 08842398XX. Once home phone rings 4 times it stops and it is immediately followed by my mobile ringing in the format 02841585XX also hanging up after 4 rings. These two numbers have to be linked.