ction of the type of transmission medium involved. 14.10 NUMBERING PLAN FOR INTERNATIONAL SIGNALING POINT CODES Table 14.3 Maximum Overall Signaling Delays Delay (msec); Message Type Processing Percent of Simple Intensive Country Size Connections (e.g., Answer) (e.g., IAM) Large-size to Large-size Large-size to Average-size Average-size to Average-size The values given in the table are mean values. Source: ITU-T Rec. Q.709, Table 5/Q.709, p. 5 (Ref. 11). to transmit messages. The velocity of propagation of the medium is a most important parameter. Table 14.2 provides information of delays for three types of transmission media and for various call distances. Although propagation delay in most circumstances is the greatest contributor to overall delay, processing delays must also be considered. These are a function of the storage requirements and processing times in SPs, STPs, number of SPs/STPs, signaling link loading, and message length mix (Ref. 11). Table 14.3 provides data on maximum overall signaling delays. 14.10 NUMBERING PLAN FOR INTERNATIONAL SIGNALING POINT CODES The number plan described in ITU-T Rec. Q.708 (Ref. 12) has no direct relationship with telephone, data, or ISDN numbering. A 14-bit binary code is used for identification of signaling points. An international signaling point code (ISPC) is assigned to each signaling point in the international signaling network. The breakdown of these 14 bits into fields is shown in Figure 14.8. The assignment of signaling network codes is administered by the ITU Telecommunication Standardization Sector (previously CCITT). All international signaling point codes (ISPCs) consist of three identical subfields as shown in Figure 14.8. The world geographical zone is identified by the NML field con- sisting of 3 bits. A geographical area or network in a specific zone is identified by the 8-bit field K through D.5 The 3-bit subfield C-B-A identifies a signaling point in a specific K J I H G F E D Area/network Signaling identification identification point identification