At the core of SIP is its ability to support media of different types. This is a significant improvement over previous VoIP protocols like H.323 which only support voice and video for its media streams. SIP doesn’t care if you are creating a voice call between two telephones, publishing a presence update, engaging in a video conference, or sending graphics commands to a shared whiteboard. SIP is completely media agnostic.
When Avaya put their Session Manager at the core of its Aura platform it took full advantage of SIP’s disregard for media content and created the concept of routing applications as part of a call flow. Avaya Aura Sequenced Applications are software entities that Session Manager invokes on behalf of the originator and terminator of SIP sessions of any type.
These Sequenced Applications are able to take full advantage of both SIP and any programming logic applicable to a user or business process. For instance, a Sequenced Application can be written that uses a person’s presence (active, away, on-the-phone, on vacation, etc.) to route an incoming call to the appropriate destination.
Another Sequenced Application could be written that identifies and blocks malicious calls.
Yet another Sequenced Application might invoke a call recorder based on a set of predetermined criteria.
Since SIP is media agnostic and Sequenced Applications are based on SIP technology, Sequenced Applications themselves become media agnostic. In other words, a Sequenced Application that processes incoming voice calls could easily process incoming video calls or instant messages. This allows an enterprise to treat their employees and customers as users and not as a collection of devices. The rules that apply to a person are invoked no matter how that person communicates or is communicated to.
Sequenced Applications differ greatly from traditional Computer Telephone Integration (CTI) programming models like TAPI (Telephony Applications Programming Interface) and TSAPI (Telephony Services Applications Programming Interface) in that CTI applications are focused on controlling the endpoint.
A CTI application can make a call or answer a call, but it can’t affect the call as it makes its way from sender to receiver. Unlike Sequenced Applications, it cannot get “in the middle” of a call and change its behavior outside of the actions an endpoint can take on it.
Successful IP department pride themselves on providing their users unique, nimble, personable, and reliable services. With Avaya Aura Session Manager, SIP, and Sequenced Applications at the core of an enterprise’s communication infrastructure there is no end to how companies can differentiate themselves from the competition.
Back-end business applications can be as much a part of a phone call as dial-tone is today. This is ground-breaking territory and only comes with SIP and the flexibility that it delivers.
Tao, Zen, and Tomorrow 
[…] me about CE, but on the top of the list are the Call Intercept Services. These are very similar to Avaya’s Sequenced Applications, but Call Intercept Services extend the concept of in-call applications to better support non-SIP […]