COLP (Connected Line Identification Presentation) can also be offered by the ISDN provider. If you've applied for COLP, you get an extended dialing protocol. You will receive feedback from your telecommunication company who picked up your outgoing call. Normally, you will get the same number as you dialed beforehand; however, with call diversion this could also be a different number. In Germany, it must be applied for, and costs extra. More information than COLP can be obtained with the help of a reverse-connected ISDN card.