SIP Trunking

Evolve voice services and make cost savings compared to ISDN

Reliable, secure and cost-effective

SIP Trunks are more cost effective than traditional connections to the public telephone network, such as ISDN.

They’re more flexible, easily adapting to changes in demand, or resilience requirements. And they’ll flex, as your organisation or locations change.

Get in touch

10+ employees, Enterprise and Public Sector

Call us at

0800 955 5590

Make an online enquiry

Why choose SIP Trunking?

Simplify your spend

Choose from our three easy-to-understand pricing options so that you’ll always be on top of your spending.

Cut cost and complexity

Move to SIP Trunking and you’ll be able to centralise and rationalise your telephony estate. It doesn’t just make life simpler, it also reduces the cost of maintaining numerous PBXs.

Scale on-demand

Whatever your business need, we give you the flexibility to add and remove capacity during busy periods, for campaigns or special events.

Get flexible phone numbers

Keep the same geographic numbers when you move office. There’s no ongoing call forwarding costs and no hassle of producing new stationery or updating online details.

Manage your inbound calls

Add on the optional SIP Trunk Call Manager to manage inbound calls to all your geographic and non-geographic numbers from our easy to use portal and mobile app.

Enhanced resilience

With options for complete active-standby or loadsharing between different sites you gain greater certainty that your telephony service will be there when you need it.

SIP Trunking from O2

Replace ISDN and traditional phone lines

SIP Trunking connectivity options

SIP over Ethernet

An Ethernet connection to the O2 network gives you telephony you can rely on, whether it’s a single dedicated connection or on our converged comms platform: O2 Gateway.

SIP over public

Connecting sites via the public internet doesn’t provide the assurance of an Ethernet connection but it’s a good option for smaller sites, or where you need a speedy setup.

SIP over Janet

SIP Trunking is ‘Janet Connected’. We maintain at least two geographically diverse connections to Janet, so you can be sure of direct traffic flow at all times.

A little bit more info

O2 SIP Trunking Product sheet for medium sized businesses: Read more about O2 SIP Trunking for medium sized businesses
O2 SIP Trunking Product sheet for larger businesses: Read more about O2 SIP Trunking for larger businesses.
O2 SIP Trunking tariff document: Get more information the O2 SIP Trunking tariff here including voice termination rates
O2 SIP Trunking price list.: Download the latest O2 SIP Trunking price list, including pricing for SIP channels, New numbers, Porting Numbers and the minute bundle options.
SIP Trunk Call Manager product overview: Read our SIP Trunk Call Manager product overview here