December 20, 2014

3 Important Roles that SIP Plays in a Contact Center

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Anyone who runs a contact center has to be concerned about issues like disaster recovery, business continuity and smooth, reliable communications, including for call transfers and between applications. Increasingly, the Session Initiation Protocol (SIP) is playing a big role in enabling those capabilities and more in contact centers.

SIP, as we’ve covered before, is a signaling protocol that handles call setup, tear down andsession management for a variety of call types, including voice and video but also extending to applications that may play into a call center environment, such as interactive voice response and recording systems. SIP also provides the basis for many other useful features, including some innovative trunking capabilities and presence technology. In the contact center, SIP plays at least three important roles, says Zach Shankle, Director of Call Center Services for Carousel Industries.

SIP Trunking Saves Contact Centers Money, Eases Disaster Recovery

“The thing we see most is people going to SIP trunks,” Shankle says. SIP trunks are an alternative to the T-1s or PRI links that companies traditionally used to connect their call centers to the carrier network, and they provide some important benefits. First, SIP trunks can be used to terminate direct inward dial (DID) lines from anywhere, so all calls can be treated as local calls. And the trunks are essentially delivered as a single pool of capacity that you can divide up among different applications as you see fit, rather than dedicating separate channels of a T-1 to various resources.

In a disaster scenario, SIP also gives companies the ability to quickly redirect their inbound numbers to an alternate site. With traditional trunks, it may take hours to redirect your inbound numbers, Shankle says. “In the SIP model, you just flip a switch and can redirect your numbers, including the local DID numbers,” he says.

What’s more, unlike T-1s or PRI trunks, with SIP trunks companies can “burst” above their normally assigned amount of bandwidth as needed. This is great for companies with seasonal demands, such as retailers, Shankle says. Instead of having to pay for lots of bandwidth that they rarely use, they can pay for what they normally use and burst above it during periods of peak demands, paying only for actual additional usage.

Improve Contact Center Call Control with SIP

SIP can also play an important behind the scenes role in helping to make sure contact center applications can seamlessly communicate with one another and that calls are never dropped. Typically, when a call comes in the phone switch handles it initially. If the caller wants to use the IVR, the call is handed off and call control gets passed to the IVR. Or perhaps it’s passed to a computer-telephony integration (CTI) app to gather some information. Again, call control is passed to the CTI app. At some point, the call likely has to go back to the phone switch, such as to pass the call to an agent; again call control gets handed off. All that creates a lot of traffic back and forth across the network and if anything goes wrong at any step – such as the IVR or CTI app being unavailable – the call gets dropped.

Dig Deeper: Download the free whitepaper: Moving to an SIP-enabled architecture

With SIP, call control remains with the VOIP call control manager, let’s say the Avaya Communication Manager. When it needs an additional resource, SIP essentially sends an invitation to that resource to join the call; but call control remains with Communication Manager. “That’s a much smoother process and we never lose call control or risk disconnecting,” Shankle says. “If the IVR doesn’t respond, we move on to the next step and we never lose the call.”

SIP Enables Presence Capabilities in Contact Centers

Another feature that is becoming increasingly important in contact centers is presence, which enables agents to see the status of other agents at a glance – on the phone, available, at lunch and so on. That capability is driven using the SIP protocol, he says, noting it works whether the agents are in the same room or in their own homes, unable to see each other. The capability helps agents get questions answered quickly, such as by sending an instant message to an appropriate expert and reporting the answer back to the caller – without having to transfer the call. For more complex matters that do require a transfer, the original agent can find another that is available and perhaps even conference the new agent in before transferring, so the caller isn’t put on hold. “It makes for faster customer service,” Shankle says.

To learn more about SIP, download our FREE whitepaper – Moving to an SIP-Enabled Architecture, or contact Carousel today to speak with one of our contact center experts.


  1. Frank Keith says:

    A very well written description of the relevance and application of SIP in a contact center environment. Bravo, Zach.

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