Connected LineIdentification Restriction (COLR) is an ISDN feature that can be used to suppress the transmission of the called party's telephone number to the calling party. Connected Line Identification Presentation
(COLP) allows the calling party to verify the called party's telephone number. COLR suppresses this function. the COLR function is ignored for security agencies, the fire brigade and emergency services. This means that the destination number is displayed even though the COLR function is activated. Call number suppression is described in ITU-T Recommendation Q.732.2.