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O2 Business SIP Trunking
What O2 Business SIP Trunking is
O2 Business SIP Trunking provides an ISDN migration path for organisations that want to retain a PBX. It can use supplier IPVPN or SD-WAN, internet services, or third-party internet access. The stated capacity ranges from 15 to 5,000 SIP channels, with larger requirements open for discussion. Features include anonymous call rejection, incoming and outbound call barring, call diverts, CLIP, CLIR, and new or ported numbers. Geographic single-line and multi-line numbers can be ported from other licensed operators. Outbound calls can use PAYG per-minute or per-call charging, or a flat-rate tariff with call allowances. An optional web portal lets administrators manage calling features, create or schedule reports, and download call logs as CSV. Each trunk has platform-side resilience across two geographically resilient points of presence; optional dual trunks can use active/standby or active/active configurations. The marketplace listing states 99.999% guaranteed platform availability under an SLA. Buyers need an approved Session Border Controller and compatible IPVPN/SD-WAN or internet access. Listed channel plans include £4.50 a month for SIPT Channel Standard, excluding underlying SIP access.
Who it suits
The service is intended for businesses with a PBX, including small businesses, enterprises, and public sector organisations. It suits buyers seeking an ISDN migration path while keeping their existing phone system.
What it does well
- Supports number porting from other licensed operators
- Optional portal provides reports and CSV call logs
- Dual-trunk active/standby or active/active configurations
- Phone support is available 24 hours a day
What to know first
- No free plan or free trial
- Approved Session Border Controllers are required
- Standard channel price excludes underlying SIP access
- Channel plans have a 24-month term
Limits
Listed channel plans use 24-month terms and a minimum of 20 users. Underlying SIP access is excluded from several channel plans, and the included-minutes and geo/network-resilient plans have a Fair Use Policy.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| SIPT Back Up Channel | Per channel per month; 24-month term; minimum 20 users · Underlying SIP access excluded | £1 a month |
| SIPT Channel Geo and Network Resilient | Per channel per month; 24-month term; minimum 20 users · Fair Use Policy applies; underlying SIP access excluded | £14 a month |
| SIPT Channel Standard | Per channel per month; 24-month term; minimum 20 users · Underlying SIP access excluded | £4.50 a month |
| IP Voice (SIP Trunking) | Per instance per month · G-Cloud 14 listing; required underlying SIP access may be additional | £4.50 a month |
| SIPT Channel Standard including mins | Per channel per month; 24-month term; minimum 20 users · Fair Use Policy applies; underlying SIP access excluded | £6 a month |
As o2.co.uk lists them, read 8 Oct 2026. The maker's own page has the final word.
Getting started
- Open the O2 Business SIP Trunking website
- Choose a SIP Trunking plan and required channel capacity
- Arrange compatible IPVPN, SD-WAN or internet access
- Provide an approved Session Border Controller configured to O2 guides
- Configure calling features and reporting through the optional web portal
Verdict
O2 Business SIP Trunking is for organisations keeping a PBX while moving to SIP connectivity. Listed pricing includes £4.50 a month for a standard channel, with underlying SIP access excluded.
Questions
Does O2 offer a free plan or trial?
No. The service is paid and has no free plan or free trial.
What platforms does it support?
The listed platform is web.
How many SIP channels can it support?
The service definition covers 15 to 5,000 channels; larger capacities can be discussed with the supplier.
Can existing numbers be transferred?
Yes. Geographic single-line and multi-line numbers can be ported from other licensed operators.
Are emergency calling and toll-free numbers available?
Yes, both emergency calling and toll-free numbers are listed.
What are the listed prices?
Plans include £1 per channel per month for a backup channel, £4.50 per channel per month for standard, £4.50 per instance per month for IP Voice, £6 per channel per month including minutes, and £14 per channel per month for geo and network resilience.
Facts from O2 Business SIP Trunking's own pages
- Audience
- O2 describes its SIP Trunking service as intended for businesses with a PBX, including small businesses, enterprises, and public sector organisations. · static-www.o2.co.uk, 8 Oct 2026
- Availability
- The marketplace listing states guaranteed platform availability of 99.999% under an SLA. · applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
- Call charging
- Outbound calls can use PAYG per-minute or per-call charging, or a flat-rate tariff with included call allowances. · assets.applytosupply.digitalmarketplace.gov.uk, 8 Oct 2026
- Connectivity
- The service can use supplier IPVPN/SD-WAN or internet services, or third-party internet access. · assets.applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
- Features
- Listed features include anonymous call reject, incoming and outbound call barring, call diverts, CLIP, CLIR, and new or ported numbers. · applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
- Headquarters
- Slough, Berkshire, UK · o2.co.uk, 28 Sept 2026
- Number porting
- Geographic single-line and multi-line numbers can be ported from other licensed operators to the service. · assets.applytosupply.digitalmarketplace.gov.uk, 8 Oct 2026
- Portal
- The optional web portal lets administrators manage calling features and view inbound and outbound call reports. · assets.applytosupply.digitalmarketplace.gov.uk, 8 Oct 2026
- Purpose
- SIP Trunking offers an ISDN migration path for buyers who want to retain a PBX. · applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
- Reporting
- Portal users can create or schedule call reports and download call logs in CSV format. · assets.applytosupply.digitalmarketplace.gov.uk, 8 Oct 2026
- Requirements
- Buyers must use approved Session Border Controllers configured to the supplied guides and provide compatible IPVPN/SD-WAN or internet access. · applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
- Resilience
- The listing states that each SIP trunk has platform-side resilience across two geographically resilient points of presence, with optional dual-trunk active/standby or active/active configurations. · applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
- Scalability
- The service definition says capacity can range from 15 to 5,000 SIP channels, with more available by discussion with the supplier. · assets.applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
- Security
- The listing reports ISO/IEC 27001 certification, Cyber Essentials and Cyber Essentials Plus, and ISO 22301 and ISO 20000 certifications. · applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
- Support
- The listing offers phone support 24 hours a day, 7 days a week, and lists target restoration times by incident priority. · applytosupply.digitalmarketplace.service.gov.uk, 8 Oct 2026
Where O2 Business SIP Trunking stands on Freedom251
- SIP Trunking Providers#18 of 27