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22.9 ATM ADDRESSING 747administrations. The signaling portion of the B-ICI specification is based on theB-ISUP recommendations, with only minor differences. In addition to signaling,and unlike B-ISUP, B-ICI includes detailed requirements for physical, data link,and network layers.22.9 ATM ADDRESSINGATM networks use two types of addresses for connection setup:1. Telephony numbering plan addresses, specified by ITU-T in Rec. E.164(Section 1.2). This type of address is called native E.164.2. ATM end system addresses (AESAs), described in the Addressing ReferenceGuide and in the User Guide of the ATM Forum [33,34].AESA are based on ISO’s network service access point (NSAP) addresses, withsome very minor differences [35]. For that reason they are sometimes referred toas NSAP AESAs or just NSAP addresses. The ATM Forum specifications definefour types of AESAs, all having a fixed length of 20 octets:1. DCC (data country code) format2. ICD (international code designator) format3. E.164 format (AESA)4. Local AESA formatDCC addressing authority rests with the ISO, who assigns a national code toeach country, per ISO 3166, and delegates authority for the domain-specific partFigure 22.9-1. AESA addressing formats. (Courtesy of the ATM Forum.)