The ultimate guide to selecting a SIP Trunking provider for your business
When deciding on a SIP trunk provider, reliability, support and contract terms are the primary considerations. Price is important but it doesn’t always indicate which service will be still operating on a busy Monday morning.
For UK companies, it’s all the more urgent. Openreach said that the legacy copper phone network will be phased out this time without delay, on 31 January 2027. If your business is using a PBX on ISDN, you’re looking for virtual lines to take the place of that technology, and SIP trunking is typically the answer.
Rather than definitions, this guide will concentrate on sensible ways to compare providers.
Begin with Your Needs, Not the Brochure
Prior to contacting any provider, write down the things you require. Quotes are only comparable if they’re based on the same requirements.
Peak simultaneous calls: this is your channel number. If you have call logs then look at call logs instead of guessing from headcount.
Numbers: Main line, direct dial-ins (DDIs), and any numbers that you want to port.
The type of your PBX: make, model, SIP support (or not).
Number of offices and if channels are to be shared between offices.
How much does an hour without cell phones cost?
A company that receives a majority of its leads inbound will have different requirements than those that do outbound calls all day.
The Questions That Separate Providers
There are a lot of things that sound alike when you first call the majority of sip trunking providers. The distinctions are found in the detail.
What are the methods used to deliver the service?
Others operate their own voice network and are directly attached to the telephone network. Others resell capacity from one of the larger carriers. Neither is necessarily superior, but it is important to recognize that you’re purchasing one or the other, as it will determine who is going to rectify any faults and how fast.
In addition, inquire how the trunks are delivered to you. Calls may be made over your standard broadband, business fibre connection or dedicated line with guaranteed quality. The more voice-critical your business is, the more valuable it is to pay for a connection which is not shared with everyone’s downloads.
What is Resilience Built In?
Ask about your connection and the provider’s platform with a SIP trunk service.
Their side: Do they have redundant data centres and if so, what happens with one of them breaks? On your end: Will automatic redirect to mobile or to another site if you lose your connection? Is it possible to install a second connection later without redoing the entire project?
What Does Support Look Like?
Review UK based support hours, fault reporting processes and ownership of the fault if it was unclear that it was on your network or perhaps on their platform. A provider who will be able to work through that with you is worth more than one who offers a slightly lower price tag.
Do They Take Security and Emergency Calls Seriously?
Criminals can use weak configuration to place expensive calls – it’s a fact of life with SIP. Discuss limits, unfamiliar transactions and encryption alerts. Also ask how the 999 calls are directed and how your address details are maintained as accurate throughout sites. Get the answers in writing.
How to read the price correctly – Cheap vs Reliable?
There are lots of folks looking for the lowest priced UK VoIP companies, and it is only natural. However, a low headline rate can be deceiving.
Examine the components of the bill:
The fee paid per channel on a monthly basis
Per number/block: typically these are for DDI and number fees
Landline, mobile, international and 03/08 rates may vary significantly for calls.
Bundles: minutes included, what happens after you use them?
One-off costs: set up, porting, gateway hardware and connection upgrades
If your plan is low-cost per channel and high cost on mobile calls, it could prove to be more expensive for your sales team than a high-cost plan with more generous bundles. Request quotes from each provider based on the actual call volume, preferably from the previous quarter.
“Best UK VoIP providers” lists are no exception. If it is not known what your PBX, site or call volumes are, it is a starting point at most. What works for a 10-member logistics firm might not work for a three-firm law firm.
Contract Terms that deserve repeats
Pay attention to these prior to signing.
Minimum term and renewal. There are certain contracts that continue automatically. Make sure to note the notice period.
Changing channels. Are you able to add channels in a hurry for a busy time of year? Are you able to cut them down for free?
Porting and exit. Do you have to do the job of moving numbers away if you leave? How long will it take?
Service levels. What guarantees does the provider offer for uptime, and what are the consequences of failing to meet this? Seek clear solutions, rather than targets.
Price changes. Are call rates subject to change during the term and if so, by how much and how much notice?
A Simple Scoring Method
Should you have three providers to choose from, rate each on a scale from 1-5 in the areas that are relevant to your business, giving a higher score to the provider that excels in these areas.
- Resilience and failover
- Ensure quality and UK availability.
- Compatibility and Migration experience with the PBX.
- Waste of money and resources due to inaccurate billing
- Contract flexibility
The cost of downtime for a business with a critical need for reliability may be more than double. If you have a small team and a small budget, you may be more inclined to consider cost, but the first three should still be considered as a minimum, rather than an option.
A Worked Example
Imagine a 30-person surveying company based in Bristol and Cardiff, on a single PBX. They require 20 channels, at both locations, and they want calls to drop to staff mobiles when either office loses connection.
The lowest Channel price is possible with Provider A, with no fail over, and basic support hours. Provider B is a little more expensive, with automatic diversion and provides more extensive UK support. Provider C is like B, except that they want a longer contract.
B is better off with the three targeted against their priorities. Though it’s not the least expensive, the cost of a day without phones would be significantly higher for the company than the difference in monthly costs.
Common Mistakes to Avoid
Making comparisons based on different estimates. Provide each provider with the same brief.
Ignoring your connection. A congested office network can’t be rectified by the best provider.
Withholding a trial. Inquire if you may try the piloting of some numbers first.
Forgetting non-phone devices. Phone lines are sometimes used for alarms, lift lines, CCTV and card machines.
Coming late to the party. Nearly always, when deadlines are nearing, provider and engineer capability constricts.When deadlines are drawing near, provider and engineer capability constricts.
There are specialists like Wavetel Business who can support your business when such a decision is being made, and any provider you are considering should be able to provide you with the terms, plan and pricing in writing.
Frequently Asked Questions
What are the qualities of a good SIP trunk provider?
Reliability and failover, UK-based support, proven compatibility with your PBX, transparent pricing based on your usage, and flexible contract terms.
Does the lowest SIP provider offer quality service?
At times, but not necessarily. Compare all costs (calls, numbers, set-up costs) and consider resilience and support.
Do I need to have a specific SIP trunk?
Not always. For many smaller offices, ordinary business fibre will do, but if the site is busier or if voice is a critical function, then a second connection or dedicated line may be warranted.
Will I be able to retain my numbers?
Yes, in most cases, by means of number porting. The timescales will vary and request realistic dates and retain old lines until it is confirmed that a switch has occurred.
Putting SIP trunking in comparison to a hosted phone system?
It depends. SIP trunking is recommended for companies that are maintaining an existing PBX system, while a hosted system is better for companies looking to eliminate on-site equipment.
Conclusion
There are only a few questions to consider when selecting a provider of business SIP trunking: How it’s supplied, how resilient it is, how good the support is and what is actually included in the contract. Price is only a part of that picture, it is not the entire picture.
The lesson to take from this is to list down what you need, ask the same set of questions from all providers and compare and contrast against the importance of your business. Timing is important, and is best done a few months before January 2027 to make the proper comparisons.
