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Wholesale SIP Trunking

You can now offer your customers an enterprise-grade telephone service

Your customers spend a small fortune on phone calls and line rental. That's money they could spend with you.

Our wholesale SIP service makes it simple to add IP telephony to your product portfolio. Your customers can keep their existing phone numbers, save money on their calls, cut their line rental costs and eliminate their ISDN bills. 

Many wholesale ISPs have belatedly entered the 'SIP trunking' market, but few can match our 15+ years of experience delivering enterprise-grade IP telephony.

To sure you get the highest service levels, we use our own soft-switches and interconnect to multiple carriers.

How does SIP work?

SIP Trunking lets your phone calls travel over an IP connection instead of over costly ISDN circuits. Retain ISDN quality while obtaining the freedom to add more capacity easily.

Why choose hSo for SIP Trunking?

Full CDR's

Full CDRs

We give you access to full Call Detail Records (CDRs) so you can bill your customers.

Advanced contention-free

We keep at least 50% available capacity on any one link, leaving ample capacity for all our services to be able to burst.


Get reliability from soft-switches in multiple data centres, and multiple high-capacity connections to the phone network.

Total number porting

You can port all UK phone numbers.

Set your own reverse DNS

We keep at least 50% available capacity on any one link, leaving ample capacity for all our services to be able to burst.

Full new number choice

Obtain new phone numbers from any UK area code.

Fraud protection

We let you cap traffic to limit exposure to fraudulent activity e.g. hacking or excessive unauthorised call spends.

Free backup dial-up service

The service supports MLPPP bonding for up to 128Kbps over ISDN.

Proven expertise

We have over 15 years of experience delivering IP telephony, and over 12 delivering SIP.

Scalable solutions

We provide solutions to consumers, home users, small and large businesses, and enterprise solutions. All services receive the same care, attention and powerful features. This enables your connectivity to grow in line with your business without having to re-invest significantly.

Additional Benefits

Enhanced resilience options

Our extra resilience options can help businesses continue to make and receive calls even if their main network connection goes down.

Easy switching

Make use of our SIP expertise to achieve as smooth a switch-over as possible. We can migrate most existing phone numbers onto our SIP platform.

Get in touch

 020 7847 4550

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