Information for prison staff
A BluePhone number has been submitted on a prisoner’s phone-list application. This page explains what the number is, how incoming calls are delivered and what BluePhone can verify. It does not ask you to reach any particular decision.
What a BluePhone number is
- A UK geographic telephone number beginning 01 or 02, hosted by BluePhone’s telecoms carrier (Telnyx).
- Assigned to one BluePhone account. Each account has one number.
- Incoming calls only. The number and the app cannot make outgoing calls, call back, add another person to a call or transfer a call.
- Calls are answered in the BluePhone app (iPhone or Android), signed in to the account the number belongs to. Our terms allow one active device per account at a time.
- BluePhone does not record calls. It has no access to, and no effect on, the prison’s own recording and monitoring, which take place within the prison telephone system.
How a call is delivered
When a prisoner dials the number, BluePhone’s service identifies the account the number belongs to and rings that account’s app over the internet. When the account holder answers in the app, the prison’s call is connected to the app.
BluePhone does not dial another mobile or landline telephone number as a forwarding destination. The account holder cannot configure one: the service has no forwarding setting.
The call path, leg by leg
For completeness: delivery to the app does involve a second, internal call leg, which BluePhone bridges to the prison’s call. That second leg is addressed to the account’s own app identity, not to a telephone number.
Based on a review of BluePhone’s production call-handling code on 28 September 2026. Credentials and security details are deliberately omitted.
- Prison telephone system → public telephone networkThe prisoner dials the customer’s UK geographic number. This is an ordinary inbound call on the public switched telephone network (PSTN).Leg A · PSTN, inbound
- Customer’s 01/02 number, hosted by BluePhone’s carrier (Telnyx)The number is dedicated to one BluePhone account. The carrier notifies BluePhone’s servers; the inbound call is held, not yet answered.
- BluePhone serviceLooks up the account that owns the number (the subscription must be active), wakes that account’s app, and starts a second call leg addressed to that account’s own SIP identity — not to a telephone number.Leg B · SIP address, created by BluePhone
- Customer’s signed-in BluePhone appThe app receives leg B over the internet (WebRTC). When the customer answers, BluePhone answers leg A and bridges leg A to leg B. If either side hangs up, the other leg is ended.Bridge · leg A ↔ leg B
| Question | Answer |
|---|---|
| Is the call forwarded to another telephone number? | No. No second E.164 mobile or landline number is dialled. |
| Is a second call leg created? | Yes. One leg, addressed to a SIP identity belonging to the account, delivered to the app over WebRTC. |
| Are legs bridged? | Yes. The prison’s inbound leg is bridged to that app leg once the account holder answers. |
| Can the customer set a forwarding number? | No. There is no forwarding setting. |
| Can the number make outgoing calls? | No. |
| Is the app required to answer? | Yes. |
Can BluePhone tell us whether to approve the number?
No. BluePhone can explain and verify its service. The establishment decides whether to approve the number under the applicable policy and local arrangements. BluePhone does not claim that its numbers are approved by HMPPS or the Ministry of Justice.
Questions about a number
Staff can call the number to carry out the checks described in the policy framework (paragraph 7.5). The call will ring the BluePhone app of the account holder.
Questions about a number can be sent to support@bluephone.app, BluePhone’s general support address, preferably from an official establishment email address with the number in the subject line. BluePhone can confirm service information where appropriate. Please do not include prisoner information in the email.
Personal information about our customers
BluePhone does not release a customer’s personal information simply because someone says they are prison staff. Requests for personal information are handled in accordance with applicable data-protection law and BluePhone’s privacy policy.
Official policy
The current HMPPS Interception, monitoring and security of prisoner communications policy framework (issue date 11 August 2026; GOV.UK publication updated 23 September 2026) says at paragraph 7.9:
“Requests for the addition of 0800 numbers as social contacts, and numbers linked to call diversion and re-routing services, must be restricted under these grounds, as such numbers/platforms can facilitate diversion to certain contacts, circumventing restrictions that have been imposed and potentially causing serious harm.”Paragraph 7.9, which also requires restrictions to be necessary and proportionate, and refers to the (unpublished) Operations Manual for exceptions.
The published framework does not define “call diversion” or “re-routing”. The description above is intended to help staff apply that wording to how BluePhone actually works; it is not a claim about how the wording must be applied. Our explainer on the policy sets out the relevant wording, including Annex C.