Using a TE411P 4 port E1 card in the UK. All the ports are TDM primary rate EuroISDN (30B+D).
My Asterisk server receives inbound calls on port1 (from the local BT exchange) and sends them out on port2 to an IVR using the Dial command. Port1 is set to pri_cpe and port2 to pri_net signalling. The IVR answers the inbound call, plays a voice file but then I need the IVR to be able to transfer the call using the call transfer capabilities within Asterisk. The Dial command that sends the call to Port2 includes the "t" option which should allow # dtmf tone to be used as a signal to put the call on hold. However, I cannot get the IVR to put the call on hold on Asterisk. The # tone can be heard by the caller, but Asterisk ignores it.
When I try exactly the same thing using an analogue FXS port for Port2 (with a suitable POTS phone connected in place of the IVR), the # tone puts the call on hold with no trouble. Have I got something wrong in the config or is there a limitation that calls just cannot be put on hold and transferred on an ISDN connection?