Setting up a SIP Trunk

Are you ready to install SIP trunking into your business’ phone system, but not sure how to do it? Read our guide to help you get started

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SIP trunking is a virtual installation on a phone system that replaces the need for physical phone lines, as calls are made and received as data sent across an internet connection. SIP trunking for businesses offers many benefits, including increased space and lower maintenance, as well as cost-savings and quicker disaster recovery options.

We’ll provide the key information you need to know about the available options for setting up a SIP trunk, including the factors to consider when deciding which installation method may be best for your business. Then, we’ll offer a step-by-step guide so you can do it yourself (providing you have the relevant skills and experience).

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How to set up a SIP trunk

Use a SIP trunking provider

It may be possible to get assistance from your SIP trunking provider. The level of customer support and technical assistance available is a key factor to consider to ensure you pick a provider that’s right for your business.

While each provider may offer a different level of support and assistance, it should be possible to contact them with your queries, whether support is provided via phone, email or live chat. Alternatively, some providers may have online guides or forums where you can get help.

Our guide to the best SIP trunking providers for more information. Or, to help you work out a budget, check out our page on SIP trunking pricing.

Hire a freelance IT specialist or an IT outsourcing company

With this option, you can hire a professional IT specialist or manager on a freelance basis to complete the task for you. Similarly, an IT outsourcing company could also be an option, depending on your business’ requirements and how many SIP trunks you need to have installed.

There will be costs to hire a professional for setting up a SIP trunk. This could be on a per hour, per day or ongoing basis, for example. However, you should consider the expense against how quickly and efficiently SIP trunking could be implemented into your phone system.

Do it yourself

Setting up a SIP trunk yourself is possible, although it may be somewhat of a challenge. You’ll need to have a fairly good grasp of IT management and coding skills, so this is perhaps more suitable for those that have worked in IT or software development.

You’ll need:

  • A computer with internet connection
  • Your PBX, SIP trunk and VoIP phone system account details
  • Your IP address
  • A gateway (to connect a non-IP phone system, if applicable)

Essentially, there are three options available when it comes to setting up a SIP trunk. These are:

  • Use the SIP trunking provider
  • Hire a freelance IT specialist or an IT outsourcing company
  • Do it yourself

Step-by-step guide to setting up a SIP trunk

  1. Log into your PBX system
  2. Select the ‘Trunks’ option
  3. Create and add a SIP Trunk – this will connect the system externally
  4. Name the Trunk
  5. Set the outbound caller ID – your business phone number, or whichever number you intend to use
  6. Set the maximum number of channels
  7. Enter SIP peer details – this is how the systems talk to each other
  8. Register the Trunk – you may need to set up to register with a VoIP provider; this may be called a ‘register string’
  9. Click ‘Submit Changes’
  10. Click ‘Apply Config’ – this is a key step, as it sets the Trunk live

Your SIP Trunk is now connected, and the PBX can connect to make and receive calls.

Alternatively, you can set the outbound and inbound routes after setting up a SIP Trunk. These routes are how the PBX knows where to send the phone call, especially if it’s a system with multiple Trunks, such as back-ups for the phone system.

  1. Check the registries or console commands for code
  2. Create an outbound route
  3. Name the outbound route
  4. Create dial patterns for phone numbers – this is based on the number of digits: e.g. in the UK, landline and mobile numbers have 11 digits
  5. Select the area code: e.g. +44, 01, 02, 03, etc.
  6. Select Trunk
  7. Click ‘Submit Changes’
  8. Click ‘Apply Config’
  9. Create inbound rate
  10. Determine the selection and name the route
  11. Select extensions
  12. Click ‘Submit’
  13. Click ‘Apply Config’
  14. Test inbound and outbound calling – this can be done through an operator panel, and by checking call status
  15. Search to show peers – these should be pinging to show the gateways are working, and/or the connection is live

What are peer details?

This involves setting up a registration with the SIP provider – the peer details set how the SIP trunk and IP system will talk to each other. You can create the code for how the systems will connect.

Note that there are many options for how to configure your phone system. The code you use will depend on your ability, as well as the level of functionality you need the system to have.

Some key points to remember are:

  • Ensure that you’re using a firewall, and an internet connection that can support SIP trunking sufficiently
  • Keep the IP address and SIP log-in details secure and private, as these can be used to access your phone system and server. It’s wise to set a strong password too
  • Check the server status – this is where any errors or issues will be raised, such as the status of the server or system
  • Only set up the SIP trunk account details once the server status is confirmed
  • Note that if there are any issues with the server or system status, these may come from your firewall, so be sure to check this
  • Remember to save changes along the way

How to decide on an installation method

There are a number of factors to consider when deciding which method will be best for installing SIP trunking into your business’ phone system. Have a think about the following questions to help you decide.

What is your skill level?

If you have some previous experience and knowledge of IT management, or coding ability, then you may be able to set up a SIP trunk independently.

However, using a professional (whether your provider or hiring a freelancer) is likely to be the best option for most start-ups.

When does it need to be ready?

Similarly, understanding how quickly you need to have SIP trunking installed and ready to use on your phone system will affect which method you use.

Doing it yourself (even for those with the necessary skills) will require you to set aside the time, taking you away from your other business duties. Decide if you can balance the time saved with the expense of hiring a professional.

How much is your budget?

Speaking of which, the amount you can afford to spend on SIP trunking is likely to be a key factor when making your selection. Setting up a SIP trunk yourself is technically free (although it will take you away from other work tasks, so bear that in mind).

However, hiring a professional will incur charges. You should also review what technical support and assistance your SIP trunking provider may be able to offer, and if there are any costs associated with this too.

Why are you using SIP trunking?

At this stage, it’s useful to think about why you’re installing SIP trunking. For example, if you run a start-up that needs one or two SIP trunks, your business’ needs are likely to be very different from a more established business that requires multiple trunks.

Likewise, specialist businesses that rely heavily on extensive phone systems (call centres, recruitment agencies, customer service companies, sales offices, PR companies or talent agencies, for example) would also have different requirements.

Therefore, the best installation method will depend on the reasons for choosing SIP trunking in the first place – whether you’re looking to cut call costs specifically, update your phone system in general, or provide more all-round cohesive communications.

Setting up a SIP trunk: A checklist

Here we outline some of the key points that need to be covered, whichever installation method you choose.

  • Do the number of SIP trunks cater for the number of phone system users?
  • Are the phones configured and set up?
  • Is there an appropriate amount (and strength) of bandwidth?
  • Are there disaster recovery plans in place?
  • Has the system been tested before going live?
  • Do existing phone numbers need to be transferred to the new system?
  • What security measures are protecting the system?

Compare SIP Trunk set-up and providers

By now, you’ve learned more about how to choose the SIP trunking installation method that’s most suited to your start-up’s requirements, as well as how to do it yourself (if relevant).

If you need to find a flexible cloud-based or virtual phone system for your company, tell us what what your business needs and we’ll match you with bespoke quote from top UK suppliers.

Written by:
Scarlett writes for the energy and HR sections of the site, as well as managing the Just Started profiles. Scarlett is passionate about championing equality and sustainability in business.
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