O2 Business SIP Trunking
O2 Business SIP Trunking provides an ISDN migration path for organizations retaining a PBX.
What O2 Business SIP Trunking is
O2 Business SIP Trunking provides an ISDN migration path for organizations retaining a PBX. Connections can use supplier IPVPN or SD-WAN, internet services, or third-party internet access. Capacity ranges from 15 to 5,000 SIP channels, with larger requirements available for discussion. Features include anonymous call rejection, inbound and outbound barring, call diverts, CLIP, CLIR, and new or ported numbers. Geographic single-line and multi-line numbers can be transferred from other licensed operators. Outbound charging can be PAYG per minute or per call, or a flat tariff with included allowances. An optional portal manages calling features, schedules reports, and downloads CSV call logs. SIP trunks have resilience across two geographically separated points of presence, with optional dual-trunk configurations. The listing states 99.999% platform availability under an SLA. Prices include £1 a month for a backup channel and £4.50 a month for a standard channel; underlying SIP access is excluded.
Good
- Supports 15 to 5,000 SIP channels
- Retains an existing PBX
- Number porting and calling controls
- CSV reporting through optional portal
- Two-point platform resilience
Watch out
- No free plan or free trial
- Underlying SIP access may cost extra
- Approved Session Border Controller required
- Some plans require 24-month terms
Who it suits
O2 describes the service for businesses with PBXs, including small businesses, enterprises, and public sector organizations. Buyers need an approved Session Border Controller and compatible network access.
Verdict
O2 Business SIP Trunking combines PBX migration, configurable calling, number porting, reporting, and resilient connectivity. Prospective buyers should account for required access, equipment, and plan-specific terms.
Plans and prices
From O2 Business SIP Trunking's own pricing page, checked 8 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| SIPT Back Up Channel | £1 a month | Underlying SIP access excluded · Per channel per month; 24-month term; minimum 20 users |
| IP Voice (SIP Trunking) | £4.50 a month | G-Cloud 14 listing; required underlying SIP access may be additional · Per instance per month |
| SIPT Channel Standard | £4.50 a month | Underlying SIP access excluded · Per channel per month; 24-month term; minimum 20 users |
| SIPT Channel Standard including mins | £6 a month | Fair Use Policy applies; underlying SIP access excluded · Per channel per month; 24-month term; minimum 20 users |
| SIPT Channel Geo and Network Resilient | £14 a month | Fair Use Policy applies; underlying SIP access excluded · Per channel per month; 24-month term; minimum 20 users |
The facts
Each one read from O2 Business SIP Trunking's own pages, with the date it was checked.
What it does
- Audience
- O2 describes its SIP Trunking service as intended for businesses with a PBX, including small businesses, enterprises, and public sector organisations.checked 8 Oct 2026
- Availability
- The marketplace listing states guaranteed platform availability of 99.999% under an SLA.checked 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.checked 8 Oct 2026
- Connectivity
- The service can use supplier IPVPN/SD-WAN or internet services, or third-party internet access.checked 8 Oct 2026
- Features
- Listed features include anonymous call reject, incoming and outbound call barring, call diverts, CLIP, CLIR, and new or ported numbers.checked 8 Oct 2026
- Number porting
- Geographic single-line and multi-line numbers can be ported from other licensed operators to the service.checked 8 Oct 2026
- Portal
- The optional web portal lets administrators manage calling features and view inbound and outbound call reports.checked 8 Oct 2026
- Purpose
- SIP Trunking offers an ISDN migration path for buyers who want to retain a PBX.checked 8 Oct 2026
- Reporting
- Portal users can create or schedule call reports and download call logs in CSV format.checked 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.checked 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.checked 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.checked 8 Oct 2026
- Security
- The listing reports ISO/IEC 27001 certification, Cyber Essentials and Cyber Essentials Plus, and ISO 22301 and ISO 20000 certifications.checked 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.checked 8 Oct 2026
The company
- Headquarters
- Slough, Berkshire, UKchecked 28 Sep 2026
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