Call Offer

General:

An extension who dials another extension number and receives busy message can invoke Call Offer/Waiting on the busy extension.

Call offer is supported in a CCS network consisting of DPNSS tie lines or private homogeneous ISDN tie lines or ISDN public external lines (for VPN). Call offer is also supported in packet-switched networks based on H.323 tie lines and/or H.323 public external lines, and even in mixed ISDN-H.323 networks (Interworking Considerations in H.323 Networks).

There is a COS (in the EX/KS and extension commands) which allows or denies the initiation of the Call Offer/Waiting request from the originating party (A party). The called (B) party has a COS which allows or denies the acceptance of Call Offer/Waiting against it. The COS of party (C), who is connected to the busy (B) party, is not checked. When a PBX operator extends a call to a busy extension, if the checking of the COS has passed, then the system will generate a Call Offer/Waiting indication automatically.

An extension calling a busy extension, can order the system to send a Call Offer/Waiting tone to an analog extension or ringing signal to a digital extension. In addition to the COS for the busy extension (B), also an AS parameter, PARNUM = 35 controls if the Call Offer/Waiting shall be permitted.

If the incoming external line uses CCS, and the external originator is an extension or PBX operator, the COS of the incoming route does not matter. Automatic Call Offer/Waiting will not be executed.

No other specific I/O data are required for Call Offer, except that network services must be supported. If network services are not supported, and if calling party is a PBX operator, the Call offer request will be discarded, and the call will proceed as basic call. For ISDN, Call offer is available even if full ISDN functionality is not supported, that is, when cooperating with an ASB 501 04 R2/n.