What is SIP trunking?

Tips & Tricks

SIP trunking is a service whereby a company with their own existing telephony servers, can connect via a service provider to be able to make and receive calls. This is especially useful for larger businesses that have already invested money in their equipment, and can save money on additional features on a hosted solution, such as monthly charges for extensions.

More specifically, companies using SIP trunking will require a PBX (Private Branch eXchange) server to connect with. A PBX can come in different forms; most commonly a physical piece of equipment that exists in their office, or a piece of a software that runs on a server either again in-house, or in the cloud.

Why use SIP trunking?

SIP trunking, and more importantly running your own PBX system, provides a far greater level of control than most cloud-based, hosted systems.

Advantages include but are not limited to;

  • The ability to control all your inbound and outbound call routing
  • Diverse call routing - the ability to set up multiple service providers for redundancy purposes
  • The possibility to configure certain usage restrictions, such as the ability to only place calls to certain destinations with outbound rules.

Generally, SIP trunking services will provide simpler pricing; charges per number on the service, cost per calling channel (1 channel generally equating to one telephone call), and per minute call charges. This is often much easier to digest than individually priced features within a cloud-based/hosted PBX system.

Due to the simpler pricing of a SIP trunking service, just paying for numbers and channels, this can be a lot more cost-effective at scale. You can add additional users yourself at any time, at no extra cost. You just need to make sure you have enough calling channels available with your service provider if the additional users will increase your call volume.

Disadvantages of SIP trunking

Running your own PBX and equipment carries its own overheads in terms of requiring a level of technical knowledge and expertise, as well as potential licencing/rental costs for any software.

A good example of such a service is FreePBX, which is a free and open source PBX system that a number of Dial 9 SIP trunking customers connect via. FreePBX can be run either on-premise, or on a dedicated server in the cloud. This comes with the obvious cost connotations of running the server(s) that power the PBX, and having to pay for either an in-house person to run and maintain, or possibly something like an IT support contract, to have a third party look after the equipment on your behalf.

Conversely, if you were to look at a hosted PBX system such as Dial 9's Business Phone, the cost, time and technical knowledge of running your own PBX is negated. That side of things is all done for you, but you still have the control to be able to configure the system yourself, adding numbers, removing users etc, at any time.

Dial 9 and SIP trunking

Dial 9 can provide SIP trunking services to those customers that have their own PBX with simple pricing. SIP trunking starts at £4.50/month - this includes a standard incoming number, and an outbound trunk connection with 4 calling channels. Additional channels can be added at £0.75/month per channel, and additional numbers carry a cost of £1.50/month/number.

Ultimately, whether you choose to go down the road of a SIP trunking service with your own PBX system, or a hosted system, it's up to you to decide what suits you best.

For more information, please take a look at our SIP trunking page on our website, or feel free to get in touch if you have any questions.

A little bit about the author

I'm Adam W, or as everyone prefers to call me - Batman. I get a lot of satisfaction out of helping our customers and am committed to making their customer experience as positive as possible. When not offering support to our customers, you'll find me gaming, listening to music or running.

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