Call Processing Functions in C#.NET

Decoder Quick Response Code in C#.NET Call Processing Functions

12:

When the MS becomes busy after the serving system provides the TLDN to the HLR but before the call to the TLDN is received by the serving system (this case is referred to as a call collision in ANSI-41) When the MS becomes inactive or unavailable after the serving system provides the TLDN to the HLR When the MS does not respond to paging or does not answer the incoming call alert When the MS fails authentication (ANSI-41 does not explicitly allow or disallow this case)

In these cases, the serving system initiates a set of call redirection processes that normally involve the steps shown in Figure 12228

The call forwarding default feature enables a called subscriber to have the network send all incoming calls addressed to the subscriber s directory number to another directory number (ie, the forward-to number) when a busy or no-answer condition (described in the previous section) is encountered From the ANSI-41 protocol perspective, a subscriber activation of the CFD feature is essentially equivalent to activating both the CFNA and CFB features simultaneously; registration of a CFD forward-to number registers a single forward-to number for both CFNA and CFB features The only reference to the CFD feature in an ANSI-41 message or parameter is in the DMH_Redirection Indicator parameter, which is primarily used for call-recording purposes Therefore, refer to the previous descriptions of the CFB and CFNA features for an understanding of ANSI-41 s support of CFD The CFD feature is generally considered to be the basic form of call forwarding that would be provided to each subscriber It enables call completion, typically to a voice mail system, when the subscriber cannot be reached, for just about any reason With this basic or default forwarding feature in effect, the subscriber can add the CFB and CFNA features to provide special handling of these conditions For example, a

If the originating system does not accept the redirection request, ANSI-41 specifies that the serving system may query the HLR for the appropriate forward-to number (via the TransferToNumberRequest operation) and forward the call itself However, this approach is less efficient in terms of the number of trunks involved since it includes the path between the originating and serving systems

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Part 2:

Normal call delivery sequence as in Figure 12-14 call setup to TLDN REDREQ [MS-B, Reason] 2 3 TRANUMREQ [MS-B, Reason] tranumreq [forward-to number] redreq MS-B is busy, does not answer, etc

Figure 1222 An example of CFB or CFNA after call delivery to the serving system: (1) Same as steps 1 through 4 in Figure 1214 (2) When the call to the TLDN arrives, the serving system determines that CFB or CFNA should be invoked (see text for reasons) The serving system sends a RedirectionRequest Invoke (REDREQ) message to the originating system, requesting that the call be redirected (3) The originating system uses the TransferToNumberRequest operation to obtain the forward-to number for the given redirection reason (ie, busy or no answer) from the HLR (4) The originating system notifies the serving system that it accepts the redirection request, releases the call leg to the serving system, and then forwards the call to the forward-to number provided by the HLR

subscriber has CFD to voice mail but wants calls temporarily redirected to a coworker if the subscriber is engaged in a call, eg, to handle particularly important calls For this purpose, the subscriber activates the CFB feature and registers the coworker s telephone number as the CFB forward-to number

Downloaded from Digital Engineering Library @ McGraw-Hill (wwwdigitalengineeringlibrarycom) Copyright 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website