What is SIP Trunking?

Session Initiation Protocol (SIP) trunking is the process of using voice over Internet Protocol in order to enable the connection of a PBX (Private Branch Exchange) with the internet. It is a streaming media and VoIP service dependent on the SIP through which Internet telephony service providers deliver unified communications and telephone services to customers who have SIP-based PBX and Unified Communications facilities. A majority of Unified Communications software applications provide audio, video, and other streaming media apps such as web conferencing shared a whiteboard, and desktop sharing.

For many enterprises, SIP trunking has become the favored means for voice communications due to its numerous benefits, including cost savings, easy-to-use framework, and the capability to expand into data and video communications. In addition to that, there are no physical lines involved that need to be maintained and the method in itself can save you around 50% or more on your monthly phone bill.

How does SIP Trunking Work?

SIP Trunking works with VoIP phone systems and is based on Session Initiation Protocol. SIP, which forms the basis of SIP Trunking, is the standard communications protocol for audio and video in a Unified Communications solution across a data network. SIP Trunking removes the need for a physical connection to a phone company. There is no wiring, hardware, or circuit boxes involved to maintain the connection to the PSTN (Phone Service Provider) since a SIP trunk is deployed virtually over your business’s present internet connection. Minimizing the need for multiple phone lines into one point of entry can dramatically reduce charges for incoming lines and the IT cost linked to the maintenance of those lines.

A phone number, or DID (Direct Inward Dialing Number), is less costly when bought in combination with a SIP trunk. Conventionally, when a DID is acquired from a phone company, charges are applied for the DID, maintenance and IT services, and the hardware connecting the shared physical channels or lines. A DID offer without these infrastructure costs is more affordable.

Why Convert from a Traditional Phone to SIP Trunking?

A SIP Trunk offers the same service and features as your conventional analog phone line. However, rather than being a tangible wire, a SIP Trunk is a “virtual” phone line that is provided by a SIP Trunk provider. They use your data circuit to connect your phone system back to their network. Since there are no physical lines to be maintained with a SIP Trunk, and due to the affordability of the VoIP structure, a SIP Trunk is significantly less costly as compared to traditional telephone service. Depending on the kind of calls, and the number of calls you are making, SIP Trunking can help you save around 50% or more on your monthly phone bill. Another reason why you should consider converting to SIP Trunking is that it can offer caller ID and DID services.

How Many SIP Trunks does your Business Need?

The number of SIP Trunk your business needs will be determined by a couple of factors. First and foremost, how many concurrent calls does your business require? As a general rule of thumb, you will need roughly one SIP Trunk for every 2 to 3 users.

Secondly, your internet connection will be a key consideration. SIP Trunks basically consume bandwidth. Based on the number of phone calls you will be making and the need for data bandwidth, you might have to extend your data circuit.

Benefits of SIP Trunking

SIP Trunking is completely different from full cloud-hosted services, such as hosted PBX. It is a valuable transitional technology that enables enterprises to take advantage of improved communications services and at the same time continue to derive value from present investment in on-premises equipment. As compared to traditional phone services, SIP Trunking brings along the following benefits.

  1. SIP trunks are not limited to delivering just voice calls. Network operators can also deliver collaboration services and unified communications over the same connection.
  2. The capacity of Phone Service Providers if usually inflexible and expensive in periods of high demand. SIP trunks are quite cheaper to maintain and much more versatile in terms of catering to your business’s changing needs.
  3. SIP trunks are dependent on broadband connections instead of managed PSTN infrastructure, which means SIP trunking service providers can tap into geographic areas where they don’t own and control the infrastructure.
Things To Know Before Buying A SIP Trunking Service

In order to prepare your organization for SIP Trunking, you need to take into account a couple of important things.

  1. How many users will be there simultaneously during your busiest hours? – Answering this question will help determine how many channels you actually require. SIP trunks facilitate easy and quick scaling, which means you may need to add or remove channels if you over or underestimate.
  2. Will your call volume stay relatively consistent on a weekly basis, or will it vary? – With SIP Trunking, you can either buy by the minute or by the channel. Answering this question will help you opt for a more flexible pricing method.
  3. Will there be a need to add or scale new users rather quickly? – This is a critical question to ask, especially when choosing between hosted and on-premises phone systems.
  4. Is your network ready for SIP Trunking? – Network considerations that should be taken into account include total bandwidth available, firewalls (critical for maintaining security both within WAN and LAN), and Quality of Service. Upgrading your present internet connection might be necessary to make sure enough bandwidth is available to carry a new system on top of usual internet usage for your company. Use this formula to get an estimate of the necessary bandwidth that will support your calls.

The number of simultaneous calls made at your company’s peak hours x 100 Kilobits per second = bandwidth needed in Mbps for calls.

Additional Resources