Processing call flows

A back-to-back user agent (B2BUA) for use in processing session initiation protocol (SIP) call flows, the B2BUA comprising one or more processors configured to:

• maintain a plurality of predetermined call flow behaviors, each call flow behavior in the plurality being self-contained and independent from other call flow behaviors in the plurality, each call flow behavior in the plurality being applicable at one or more given call flow stages to provide one or more given actions for addressing a given call flow scenario;
• in response to occurrence of a given trigger event in a given SIP call flow, pre-filter the plurality of predetermined call flow behaviors to produce a shortlist of call flow behaviors from the plurality of call flow behaviors, wherein the shortlist of call flow behaviors is also produced by performing a hashing operation on the plurality of predetermined call flow behaviors;
• perform a sequential evaluation of call flow behaviors in the shortlist of call flow behaviors until a sequentially evaluated call flow behavior matching preconditions of all of the respective call flow behaviors are identified;
• selecting the sequentially evaluated call flow behavior, wherein the selecting is performed at least on the basis of the shortlist of call flow behaviors produced from the hashing operation;
• and
• execute the identified call flow behavior to address a call flow scenario in relation to the given SIP call flow.

A non-transitory computer-readable storage medium storing instructions that, if executed by one or more processors of a back-to-back user agent (B2BUA), cause the one or more processors to:

• maintain a plurality of predetermined call flow behaviors, each call flow behavior in the plurality being self-contained and independent from other call flow behaviors in the plurality, each call flow behavior in the plurality being applicable at one or more given call flow stages to provide one or more given actions for addressing a given call flow scenario;
• in response to receipt of a network or application command message or a timer firing in association with a given SIP call flow, perform, on the basis of one or more SIP call attributes associated with the given SIP call flow, a hashing operation on the plurality of predetermined call flow behaviors to produce a shortlist of call flow behaviors from the plurality of call flow behaviors;
• sequentially evaluate call flow behaviors in the shortlist of call flow behaviors until a call flow behavior matching all of the preconditions specific to the respective call flow behavior is identified;
• and
• cause execution of one or more actions associated with the identified call flow behavior to address a call flow scenario in relation to the given SIP call flow.