Ask three suppliers for a quote and you’ll often get three completely different formats. One price per channel, another bundles minutes, and a third adds fees you didn’t expect. That’s why comparing a SIP trunk service on price alone can be misleading.
This guide breaks down how pricing works so you can compare offers on the same basis.
The Main Pricing Components
Most providers combine several elements. Understanding each helps you spot where costs really come from.
Channel fees
A channel carries one simultaneous call. You typically pay a monthly fee for each channel, so ten channels means up to ten calls at once. Some providers offer unlimited channels with usage-based billing, which can suit businesses with unpredictable peaks.
Number costs
Each DDI or number range usually has a monthly rental. Geographic numbers, such as 0161 or 020, are common, while non-geographic and 03 numbers may be priced differently.
Call charges
Some providers include bundled minutes to UK landlines and mobiles. Others charge per minute. Check whether “unlimited” is subject to a fair usage policy, and how mobile and international calls are billed.
Set-up and porting fees
Number porting, configuration and testing may be charged as one-off fees. Some providers waive them on longer contracts, so ask.
Add-ons
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Bundled or Pay-As-You-Go?
Neither is automatically cheaper. It depends on your call profile.
Bundled minutes suit predictable, moderate usage. A firm making steady calls to UK numbers will often get simpler bills and better cost control.
Pay-as-you-go suits businesses with low or irregular volumes, but heavy outbound callers can find costs climbing quickly. Review three to six months of call records before choosing.
Watch the Fine Print
A low headline rate can hide costs elsewhere. When comparing suppliers, look at:
- Billing increments: per-second billing generally costs less than per-minute
- Connection fees: small charges per call add up for high-volume users
- Minimum spend: some contracts require a minimum monthly commitment
- Contract length: 12, 24 and 36-month terms change the equation
- Early exit fees: worth knowing if you expect to move premises or change systems
Put quotes in a spreadsheet and calculate total cost over the full term, not just a monthly figure.
Cheapest vs Best Value
Searching for the cheapest UK VoIP providers will return plenty of low-cost options, and some are perfectly good. But price should be weighed against support quality, resilience and contract flexibility.
Think about what an hour without phones costs your business. For a dental practice or a sales team, it’s more than the monthly saving on a cheaper trunk. That doesn’t mean paying more automatically improves service, but it does mean asking what’s behind the price.
Where Savings Actually Come From
Moving away from ISDN often produces real savings, mainly because:
- You stop paying for line rental on physical circuits
- You can right-size channels rather than buying in blocks of 30
- Calls between sites can run over the same trunk or platform
- Call rates to mobiles and international destinations may be lower
The scale of the saving varies by business, so get quotes based on your own usage. Avoid any provider promising a specific percentage without seeing your bills.
Costs Outside the Quote
Some expenses won’t appear on a supplier’s price list:
- Internet upgrades: you may need a better line or a backup connection
- PBX licences or upgrades: older systems may need SIP licences or a gateway
- Firewall or SBC: you may need equipment to secure and manage voice traffic
- Staff time: internal effort for testing and coordination
Budget for these early so the business case holds up.
Example: A Logistics Company With Two Depots
A regional logistics firm runs two depots, each with an ISDN line and a small PBX. They make many calls to mobile drivers and a handful to European suppliers.
Their old bill includes line rental, per-minute mobile charges and a maintenance contract. By moving to SIP trunk Providers with bundled UK mobile minutes, a European rate card and right-sized channels, they can simplify billing and remove line rental. The actual saving depends on call volumes, but the structure is easier to predict.
If you’re building a shortlist, Wavetel Business is one supplier you could include in your comparison, alongside others, to see how pricing, contract terms and support stack up.
How to Get Comparable Quotes
Give every supplier the same brief:
- Number of channels and DDIs
- Estimated monthly call minutes by type (local, national, mobile, international)
- Phone system make and model
- Site count and internet connection type
- Preferred contract length
Same brief, same basis. That’s the only fair way to compare.
FAQs
How much does a SIP trunk cost per month?
It varies by provider, channel count and call usage. Ask for a quote based on your own call data
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Is SIP trunking cheaper than ISDN?
Often, especially for businesses that were paying for more channels than they used. It isn’t guaranteed, so compare against your current bill.
Are there hidden costs?
Possibly. Check porting, configuration and support charges, plus any equipment or internet upgrades you may need.
Should I sign a long contract for a better rate?
Only if you’re confident in the provider. Shorter terms give flexibility if service disappoints.
Conclusion
Good SIP trunk pricing is transparent, based on your real usage and clear about extras. Compare total cost over the contract term, ask about billing increments and fair usage, and budget for network and equipment changes. A slightly higher quote from a reliable supplier can be better value than the lowest price with weak support.
