SIP Trunking

Connect your PBX to the PSTN in minutes with Callroute SIP Trunking

Why choose Callroute SIP Trunking

By porting your telephone numbers to Callroute you’ll have the agility to connect them to the telephony environment of your choice in minutes. Never worry about porting your numbers again.


Integrate SIP trunks with any phone, UCaaS, CCaaS platform


Flexible SIP trunks that automatically react to demand


Enjoy 99.99% availability with our robust network


SIP channel based model allows you to grow

Cost efficient SIP trunking

Our SIP trunk service is charged per-channel. With modern day internet based communication increasing, the number of SIP channels per user is approx 13 users to 1 SIP channel.

Per-channel pricing means you are able to benefit from substantial cost savings compared to a per-user based charging model.

SIP trunk features

Highly available SIP trunk solutions for organizations of any size.

Flexible pricing

Pay as you go month-to-month or fixed annual commitment

Inclusive minutes

Enjoy 300 minutes of UK domestic calling per channel

Auto scaling

Scale up your SIP trunks to meet current demand

Secure Calling

Ensure your conversations are secure with encryption


Detailed call reports enable you to track your usage

Call recording

Record PSTN calls for customer success training & compliance


Use your SIP trunk with any calling platform


99.99% availability built-in with multi-layered resiliency

SIP Trunking FAQs

What is SIP Trunking?

SIP Trunking replaces the traditional phone line (ISDN or analogue) and typically uses the internet to connect your on-premises phone system (eg PBX) to the PSTN.

What is the UK PSTN switch off?

In 2017 Openreach announced that they are turning off the old analogue based PSTN in 2025. PSTN telephone lines include ISDN which many businesses have, these could be ISDN2 (BRI) or ISDN30 (PRI). Additional information can be found on BT’s website.

How is Callroute’s SIP Trunking solution different from others?

We offer pooled capacity across trunk locations and a unique self-service portal to allow easy migration away from traditional PBX environments to services like Microsoft Teams in just a few clicks. Enabling agility is our speciality.

How many phone lines do I get with a SIP Trunk?

There is no maximum number of phone lines (channels) per SIP Trunk, you can have as many as you like. There is, however, a minimum count of 5 channels per deployment.

How many phone numbers can I get with a SIP Trunk?

There is no maximum number of phone numbers. Port or buy as many phone numbers as you need. 

Are there any setup costs for a SIP Trunk?

There are no set-up costs for SIP Trunks as our platform is self-service. However, there may be costs associated with number porting (if required).

Intermittent Microsoft Teams calling issues reported globally. This issue appears to be affecting all Microsoft customers worldwide. Microsoft are currently investigating the issue. All Callroute systems are fully operational. More information will be provided as soon as possible.