I know DAHDI uses the Libpri library, so does Libpri support ISDN supplementary services like the ISDN Hold?
Asterisk has a call hold feature too, but the difference to the ISDN-hold is that when a call is put on ISDN hold the allocated B-channel gets free for another call, while the first is on hold.
Is this possible using a DAHDI BRI card?
The ISDN hold is described here: itu.int/ITU-T/recommendation … x?rec=2347
I have not personally verified it works, but yes, libpri and sig_pri in Asterisk do support the ISDN hold messages / protocol.
In chan_dahdi.conf you will want to set moh_signaling=hold.
Thanks for the information.
What do I have to change in the dialplan to give all SIP-User the possibility to put a call from ISDN into the ISDN-Hold state?
I believe what was meant was that ISDN hold was recognized incoming from the ISDN line. SIP users can’t even put an outgoing SIP channel into a SIP (a=sendonly) state.
What I need is, the possibility, that a SIP user can put a call from the ISDN on the ISDN-Hold state. So that the ISDN B-Channel used by that call gets free for another call, while the first caller is on Hold.