Hi Denis, With Nokia E51 AT+CHLD=11 returned ERR0R, AT+CHLD=0 and ATH returned OK however they did not have effect to the call. AT+CHUP returned OK and call was terminated (Caller received busy signal). RING AT+CHLD=11 ERROR RING RING AT+CHLD=0 OK RING RING ATH OK RING RING AT+CHUP OK Regards, Marko