Why are SIP trunks Needed in VoIP?

VoIP is no longer a new technology in 2016. It has been steadily gaining momentum over the last two decades and is now set to replace the PSTN in many countries by 2025. Yet not many people and organizations understand the terminology, its requirements or even how it can be used effectively.

The first point to remember about VoIP is that it does not refer to a specific piece of equipment, software or even standard. It simply means voice is transmitted over IP networks rather than copper lines. So it can be implemented in a number of different ways and can utilize various types of codecs, protocols and equipment.

The Two ‘Types’ of VoIP

SIP trunks and hosted VoIP are two of the most popular implementations within the enterprise segment. Just like how desktops and laptops are both computers while still offering a different experience for end users, SIP trunks and hosted services are different ways of deploying IP calling.

With hosted VoIP, both the phone service and enterprise PBX are hosted online and delivered over the Internet to clients. There is no on premise equipment to maintain or control. SIP trunks on the other hand refers only to the connection between on premise PBX systems and the ITSP. The organization has to purchase and maintain SIP compatible PBX boxes which can utilize the SIP trunk to make and receive calls.

What are SIP Trunks?

The word trunk is not actually applicable to VoIP technology but is rather a remnant of analog trunks that were used in the PSTN system. In the older technology, a trunk referred to a physical bundle of wires that connected the organization to the phone carrier. In SIP trunking, the physical wires are replaced by an Internet connection to the ITSP. It may not make much sense to refer to it as a trunk but the terminology has become accepted in the VoIP community.

Contrary to hosted VoIP services, SIP trunks do not provide PBX features to the enterprise. The organization has to have an IP PBX that can make use of the SIP trunk. So whether or not the business has access to a certain feature depends upon the PBX system and its configuration, rather than the ITSP or the SIP trunk provider.

Why are SIP Trunks Needed?

One of the chief benefits of hosted VoIP is that the organization does not have the hassle of maintaining equipment or software on its own. But with SIP trunking, businesses need to have in house expertise to set up and maintain the PBX box. They have to invest in acquiring the software or developing their own solution from open source code. It is not surprising then that SIP trunks are viewed as more trouble than they’re worth.

However SIP trunks do have their own advantages over hosted VoIP. For one thing organizations do not have to depend on an external contractor to deliver much needed features. They remain in control of the software and can customize it as per their own requirements. They do not have to depend on the vendor to upgrade the software when new features are introduced or updates are launched by developers.

It is especially true for large multinational corporations which differ considerably in their requirements from enterprise phone systems. Businesses may find it difficult to customize hosted services to their liking and SIP trunks are a significantly better alternative in that respect.

Another advantage of SIP trunks is the cost involved. Although it may require more significant upfront investment, the variable component of cost i.e. the cost per call is significantly less than purchasing hosted services from external parties in the long term. So it is much more cost effective for organizations that have high call volume – especially international calls.

Requirements for SIP Trunks

Before opting for SIP trunks, organizations should evaluate the requirements for trunking and see that the business is prepared. The maximum number of simultaneous or concurrent calls will determine bandwidth requirements as well as the total cost involved for the new system.

Analog fax machines, security alarm systems and even some credit card machines may not work with SIP trunks or need PSTN lines to function efficiently. These considerations should be kept in mind so that the business can decide whether to route all voice communications through VoIP or to retain a few landlines for legacy functionality.

Disaster or emergency backup is another crucial consideration. If something should happen to your internet connection, it may very well bring down your phones with it. It can be anything from a natural disaster to software errors. Some vendors offer built-in failover protection by re-routing calls to a specified landline or phone number.

All that considered, SIP trunking has many benefits that may not be apparent at first glance but are very useful for many businesses and hence should not be ignored when upgrading to VoIP.