SIP Trunking

Our SIP Trunks provide Reliable Voice ServicesIncreased FlexibilityInternational Breakout

Connecting your PBX to our network

Great Call Quality

Sound quality is improved through our engineered core network and use of latest codecs.

Stable & Reliable

Years of core up time is expected and delivered by careful engineering and a team dedicated to delivery.

Instant Provisioning

Need more voice channels? Want 100 London numbers? Get them instantly via us.

What is a SIP Trunk?

A SIP Trunk is the virtual link between your PBX and the PSTN over the internet. It allows you to make outbound calls and receive inbound calls using an IP connection (VoIP) rather than a traditional ISDN/PSTN line. With ISDN being phased out and moving to all-IP, SIP Trunks will be essential.

Why use an A1 SIP Trunk?

Voice networks are moving to SIP. We began this move over 15 years ago as it appeared obvious that true convergence was always going to happen. SIP has become the preferred service for business.

  • Provide flexible and resilient voice services
  • Maximise investments and leverage your IP infrastructure
  • Simplify a business’s phone system operation
  • Facilitate the switch from ISDN to all-IP services

Converting to SIP is easy, let us bring modern day flexibility to voice.

Want resilient voice services?

Use our network to deliver calls and services when and how you want them.

Key Benefits

If you are still using ISDN or moving from an analogue PBX, switching to an IP-based communication service is essential. Here are some benefits of SIP Trunking:

Increased Flexibility

Easily add and scale down as required on demand. Add capacity without any need to install physical lines.

Rapid Deployment & Easy to Use

Fast and simple setup. Connecting new geographic locations enables you to get a business up and running quickly.

UK & International Numbers

Need more voice channels? Want 100 London numbers? Get them instantly via us.

Number Porting

Moving location, country, or just want to move to SIP? We realise numbers are essential to you, so a dedicated provisioning team looks after the process.

International SIP Breakout

Facilitate global working. Ensure each country can make calls to the emergency services and receive a local call that’s not in an international call price bracket.


Find out that a PBX is down before your customers do. Monitoring and recovering from a number of voice issues can easily be set up on our portal.

Choosing the Right SIP Provider

Not all SIP providers are the same - we believe in adding value to the SIP trunks by the way of reliability; network topology; fraud prevention; CLI presentation; call recording; number porting & provisioning and UC&C. In this very competitive market, it’s the added value which enables our partners to deliver high-quality working solutions.

  • Secure network and fraud detection & prevention
  • Own network
  • Competitive Pricing
  • Number Provisioning and Number Porting
  • Support
  • Interoperability
  • Resilience

Converting to SIP is easy, let us bring modern day flexibility to voice.

Let’s Get in Touch


Call, email or drop us a message