UK Phone Codes: *#06#, *#21# and Call Forwarding

Last checked: 8 September 2026

Type *#06# into the Phone app to display your IMEI. To investigate missed calls, start with your call-forwarding settings. A star-and-hash code can show a setting or change a service; the exact sequence matters.

People often call these short codes, star codes, MMI codes or USSD codes. MMI describes commands entered through the handset interface; USSD is a network messaging mechanism. Not every star-and-hash command uses USSD. Short dialled numbers for customer service and voicemail are another category.

Start with information-only checks

The forwarding checks depend on your mobile provider, plan and handset. An error is not proof that forwarding is off. These checks do not detect spyware, and a voicemail destination is not by itself evidence of interception. Forwarding ordinary mobile calls also does not forward SMS, WhatsApp or email.

Codes that change settings

Activation and cancellation codes deserve a separate decision. For example, ##002# requests erasure of all call-forwarding registrations on a supporting service. That can remove voicemail diversions as well as office routing. It is not an anti-hacking tool.

If you want to stop a particular divert, first identify it and follow the specific cancellation instructions. Do not copy a destination number from a stranger's message. Use only the office, colleague or voicemail destination you intended and have verified.

A practical routine for business phones

When issuing a handset, record the device model, assigned user, mobile number and IMEI in a restricted asset register. A dual-SIM phone may show two IMEIs. Record both where relevant, without publishing screenshots of identifiers.

Before changing routing on a shared business number, ask the person responsible for the line what should happen when it is busy, unanswered or switched off. Note the current destinations and agree how voicemail will be restored. After an authorised change, call the number from a different phone and check the outcome.

When the phone rejects a code

Use the built-in Phone app, check the selected SIM and read the provider's current instructions. If ordinary calls also fail, investigate service or SIM problems first. If only the code fails, the handset or account may not support that method. Our invalid MMI code guide explains the next checks.

For voicemail access, use your provider's official help page. Mobile voicemail numbers and landline voicemail numbers are not interchangeable.

Frequently asked questions

Does *#06# change anything?

It displays the device identifier; it does not unlock, reset or locate the phone.

Does *#21# show whether my phone is tapped?

No. It requests a forwarding status. Neither an enabled nor a disabled response determines whether a phone is compromised.

Do the codes work on every UK network?

No guarantee applies to every plan, handset or calling service. Use the settings menu or ask your provider when a command is rejected.

Sources

• ETSI MMI specification, section 6.5 and Annex B
• EE: finding an IMEI
• Apple: forwarding settings
• Android: carrier-controlled supplementary services

Related guides

• Latest business phones
• Compare phones for your team
• Call forwarding codes and settings
• Find your IMEI with *#06#