User's Manual

Voice API Programming Guide — June 2005 179
R2/MF Signaling
The incoming register backward signals can request:
• Transmission of address
– Send next digit
– Send digit previous to last digit sent
– Send second digit previous to last digit sent
– Send third digit previous to last digit sent
• Category of the call (the nature and origin)
– National or international call
– Operator or subscriber
– Data transmission
– Maintenance or test call
• Whether or not the circuit includes a satellite link
• Country code and language for international calls
• Information on use of an echo suppressor
The incoming register backward signals can indicate:
• Address complete - send category of call
• Address complete - put call through
• International, national, or local congestion
• Condition of subscriber’s line
– Send SIT to indicate long-term unavailability
– Line busy
– Unallocated number
– Line free - charge on answer
– Line free - no charge on answer (only for special destinations)
– Line out of order
Note: The meaning of certain forward multifrequency combinations may also vary depending upon their
position in the signaling sequence. For example, with terminal calls the first forward signal
transmitted in international working is a language or discriminating digit (signals I-1 through I-10).
When the same signal is sent as other than the first signal, it usually means a numerical digit.
See the following tables for the signal meanings:
• Table 24, “Meanings for R2/MF Group I Forward Signals”, on page 180
• Table 25, “Meanings for R2/MF Group II Forward Signals”, on page 181
• Table 26, “Meanings for R2/MF Group A Backward Signals”, on page 182
• Table 27, “Meanings for R2/MF Group B Backward Signals”, on page 183