Have you selected R2-pulse.
R2-PulseR2 line signaling type ITU-U Supplement 7, typically used for systems that employ satellite links (where a Tone/A bit is pulsed).
try command -- proceed-to-send
ITU pulsed line signaling (S-7) ACKs the seizure with a proceed-to-send signal (150 ms pulse). A variant of this signaling over satellite links does not use this signal. If this is configured, the router does not ACK the seizure for incoming calls and does not expect ACK for outgoing calls. This affects pulsed line signaling calls only. Not supported on AS5800 yet.
http://www.cisco.com/en/US/tech/tk652/tk653/technologies_tech_note09186a00800942f2.shtml
