es. For instance, there are four types of address message identified by HO = 0001, and H1 identifies the type of message, such as the following: Address Message Type Initial address message IAM with additional information Subsequent address message Subsequent address message with signal unit Moving from right to left in Figure 14.11, after H1 we have the call party subfield consisting of 6 bits. It identifies the language of the operator (Spanish, English, Russian, etc.). For example, an English-speaking operator is coded 000010. It also differentiates the calling subscriber from one with priority, a data call, or a test call. A data call is coded 001100 and a test call is coded 001101. Fifty of the 64 possible code groups are spare. Continuing to the left in Figure 14.11, two bits are spare for international allocation. Then there is the message indicator, where the first two bits, B and A, give the nature of the address. This is information given in the forward direction indicating whether the associated address or line identity is an international, national (significant), or subscriber number. A subscriber number is coded 00, an international is coded 11, and a national (significant) number is coded 10. Bits D and C are the circuit indicator. The code 00 in this location indicates that there is no satellite circuit in the connection. Remember that the number of space satellite relays in a speech telephone connection is limited to one relay link through a satellite because of propagation delay. Bits F and E are significant for common-channel signaling systems such as CCIS, CCS No. 6, and SS No. 7. The associated voice channel operates on a separate circuit. Does this selected circuit for the call have continuity? The bit sequence FE is coded: Bits F and E Meaning Continuity check not required Continuity check required on this circuit Continuity check performed on previous circuit Spare CCITT SIGNALING SYSTEM NO. 7 Bit G gives echo suppressor information. When coded 0 it indicates that the outgoing half-echo sup