Every once in a while, there comes along a call center technology that disrupts (in a good way) business as we know it. Session Initiation Protocol (SIP) is one of those technologies. And though it has been around for over a decade, there are organizations where the use of SIP has been limited to internal private networks. While using SIP to connect within a private domain has its advantages, the benefits are far greater when you consider switching to SIP Trunking or SIP PSTN connectivity with carriers. Let’s review why SIP & SIP Trunking should be a core part of your communications strategy. But first, let’s get some basics out of the way.


Defining SIP (in a nutshell)

SIP is a call setup protocol that operates at the application layer. It does the handshake between devices to establish the connection. After that, a separate set of protocols are used to do the actual voice and data transfer.

In today’s IP based communication environments, SIP is a foundational protocol that is used and supported by telephony hardware and software manufacturers. The protocol is elegant, text based, and is derived from the basic request and response model of HTTP. It is forward compatible, and works with IPv4 as well as IPv6.

But SIP does more than just session setup. It also registers devices in DHCP environments, determines the media capabilities of sessions, and helps manage sessions for functions such as conferencing, transfers and call terminations.

SIP trunk is a service that connects private networks to the Public Switched Telephnoe Network (PSTN) through carrier interfaces, or with an Internet Telephony Service Provider (ITSP). It allows VoIP communication to extend beyond corporate firewalls and uses SIP as the protocol for the handshake between the carrier and the private network.

A Positive ROI case for SIP Migration

The cost equation of using a PRI vs SIP trunk is very strongly in favor of using a SIP trunk and a SIP implementation. There are three areas of savings:

  1. You can replace 30-40 PRIs or TDM circuits with a single ethernet circuit that will support voice and data over a single dedicated SIP trunk.
  2. Replacing the PRIs will also allow you to eliminate IP/PSTN gateways that convert TDM to VOIP and vice versa.
  3. You will now have the opportunity to negotiate better carrier rates for long distance, outbound calls, and toll-free calls. SIP session pooling can also be leveraged to consolidate costs over multiple SIP trunks.

On average, you should be able to achieve close to 50-60% savings annually by switching from legacy TDM/PRI lines to SIP Trunking. For more information on how to calculate the cost of a SIP trunk, see Andrew Prokop’s blog post on this topic.


The Hidden Benefits of Using SIP

There is an undeniable cost advantage of switching to SIP trunks. But there are other considerations as well that can bolster the case to migrate. Here are the considerations beyond cost savings:

  1. Simpler Integration:

SIP is now a universal protocol that is used by communications hardware and software. If you are using a PBX that is less than 10 years old, chances are that it is SIP ready. In fact, special VoIP gateways need to be used to convert the TDM calls to VOIP and vice versa. So, the more SIP friendly your edge infrastructure, the less interfacing devices you will need for systems to talk externally and across networks.

  1. Easier Maintenance:

Moving to SIP trunking is an opportunity to centralize and simplify the telephony infrastructure, making it easier to support. Because SIP is an open standard, there are a variety of tools such as Oracle’s EOM that can monitor and resolve SIP/VoIP issues within minutes.

  1. Scalability:

Because SIP trunking is done virtually over an ethernet connection, scaling up or down can be done very quickly and efficiently. While capacity planning is still required, the actual act of increasing the capacity then becomes a software change as opposed to hardware installation and routing of new circuits.

  1. Easier Outsourcing and Call Re-routing:

Onboarding outsourced call center site/agents can get complicated and expensive when using legacy trunking. With a SIP trunk, call re-routing to backup locations and to outsourced call centers requires simple registration of the SIP end-points into a consolidated and highly available telephony infrastructure (ACD/PBX).

  1. Access to New Services:

As carriers roll out new data intensive services, they will require VoIP capability to provide these services to your organization. Migrating to a SIP trunk will get you easier access to these services without needing additional data transformations.  Examples of such carrier services include:  Cloud ACD, Call Recording, Voice Analytics, etc.

  1. Foundation for Consolidation:

For companies that have grown through acquisitions or those that have multiple call centers, switching to SIP trunks makes it possible to consolidate infrastructure across locations. Now agent phones, regardless of location, become SIP end points that connect to a central telephony infrastructure. This leads to even more cost savings, process efficiencies, and reduced maintenance overhead.

Other Considerations with migrating to SIP/SIP trunks

When implementing a SIP trunk, a session border controller (SBC) will be required for security and interoperability reasons. For corporations, SBCs secure the telephony edges while providing the ability to facilitate data exchange with public and private networks using existing telephony equipment (PBXs/ACDs), and with external cloud solutions (such as IVRs).

A switch to SIP trunking needs to be well thought through and needs to be part of a bigger initiative to manage the new Unified Communications infrastructure at your organization. Consider partnering with firms that have experience in designing and managing contact center infrastructures when you consider a move to SIP trunking. This will reduce the internal burden of ramping up resources on new technologies and ensure you realize all of the potential benefits from SIP.

The Bottom Line

The case for migrating to SIP/SIP Trunking has many benefits including:  cost, interoperability, scale, simplification through consolidation and centralization.  As each carrier and vendor has their own nuances with supporting SIP, it is important to have the big picture view of SIP adoption and its benefits.  It is essential to partner with an experienced provider to ensure SIP is implemented correctly ensuring maximum realization of all the benefits SIP can provide.  For help with discussing your case for a SIP implementation, feel free to contact us.

Categories: SIP


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