O2 Voicemail Number: Dial 901 — Quick Reference for Business & Personal Use

Need the voicemail number O2 assigns to every handset? You are in the right place. Below you will find the short-code displayed prominently for fast reference, step-by-step instructions for accessing your mailbox from any phone, and — if you run a business — a smarter alternative to standard O2 voicemail that most teams never consider.

The voicemail number O2 provides is 901 on all O2 pay-monthly, pay-as-you-go, and business contract handsets. The same short-code works across O2-powered MVNOs such as giffgaff. Tesco Mobile — also carried on the O2 network — uses a different short-code: 222.

How to Access O2 Voicemail From a Different Phone

There are times — particularly in a business setting — when you cannot reach your O2 handset but still need to retrieve messages. Rather than dialling the standard voicemail number O2 provides (901), you can access your mailbox remotely from any landline or mobile:

1. From any landline or mobile, dial your full O2 number (e.g. 07XXX XXXXXX).
2. Wait for the voicemail greeting to begin playing.
3. Press * (star) to interrupt the greeting.
4. Enter your four-digit voicemail PIN when prompted.
5. Follow the menu options to listen to, save, or delete messages.

Tip: If you have never set a PIN, O2 assigns a default. You can reset it by dialling the voicemail number O2 uses — 901 — from your handset and following the PIN-change menu, or via the My O2 app under Account > Voicemail Settings.

O2 Voicemail Number vs Other UK Networks

For quick comparison, here are the voicemail short-codes for the UK's major networks. As you can see, the voicemail number O2 assigns (901) is unique — so if you have recently switched networks, make sure you update your speed-dial:

For full setup walkthroughs, PIN creation, greeting recording, and troubleshooting for O2 voicemail, see our comprehensive O2 voicemail guide.

Why Businesses Should Look Beyond the Standard Voicemail Number O2 Provides

Dialling 901 is perfectly adequate when you are checking personal messages, but for any business that relies on mobile calls — sales teams, field engineers, account managers — the standard voicemail number O2 offers introduces real operational problems:

• Single mailbox per SIM — there is no shared inbox, so if a colleague is off sick their messages sit unheard until they return.
• No transcription — you must dial 901 and listen to every recording in sequence, which wastes time during a busy working day.
• No email or CRM integration — voicemails are siloed on the handset and cannot be forwarded, logged, or searched.
• No intelligent routing — when a call goes unanswered it drops straight to voicemail instead of trying a colleague, a hunt group, or a reception desk.
• No analytics — you have no visibility of how many calls are going to voicemail, peak missed-call times, or average response rates.

If any of these issues sound familiar, it may be time to explore a more capable solution. Request a free, no-obligation quote and we will show you exactly what is possible.

How VoIP Replaces (and Improves on) O2 Voicemail for Business

A hosted VoIP or unified-communications platform sits alongside — or replaces — your O2 mobile contracts and gives your team enterprise-grade call handling without the enterprise price tag. Here is how it compares to the basic voicemail number O2 provides via 901:

Crucially, you do not have to abandon O2 to benefit. Many of our clients keep their O2 business mobiles for data and on-the-go calls while routing their main business number through a VoIP platform. Unanswered calls hit the VoIP voicemail — with transcription and email delivery — rather than the basic voicemail number O2 defaults to. The result is faster response times, fewer missed opportunities, and a far more professional impression on callers.

Can I Forward O2 Calls to a VoIP Voicemail Instead of 901?

Yes. O2 supports conditional call forwarding using standard GSM divert codes. You can redirect unanswered, busy, or unreachable calls to a VoIP number of your choice rather than allowing them to fall back to the default voicemail number O2 assigns:

• Forward when unanswered: **61*[VoIP number]# then press call.
• Forward when busy: **67*[VoIP number]# then press call.
• Forward when unreachable: **62*[VoIP number]# then press call.
• Cancel all diverts (revert to 901): ##002# then press call.

This is a popular setup for small businesses that want to keep their O2 SIMs but gain the advanced voicemail, auto-attendant, and call-routing features that come with a hosted VoIP system. Our team can configure everything for you — there is nothing to install and no disruption to your existing O2 service.

Frequently Asked Questions

Is 901 the only voicemail number O2 uses?

For dialling from your own O2 handset, 901 is the only short-code you need. It works on all O2 tariffs — pay-monthly, pay-as-you-go, and business contracts. If you are calling from a landline or a different mobile, you should dial your full O2 number instead and press * when the greeting plays to enter your PIN and access your messages.

Is it free to dial the voicemail number O2 provides?

Dialling 901 from your O2 handset is free. However, listening to voicemail messages may use your inclusive minutes depending on your tariff. If you are on a pay-as-you-go plan without an active bundle, standard airtime charges may apply. Check your O2 plan details or the My O2 app for confirmation.

What if dialling 901 does not work?

If you dial the voicemail number O2 assigns and hear an error message or the call fails, try the following:

• Check your signal — voicemail requires a network connection to dial 901.
• Restart your phone — a quick reboot can resolve temporary network registration issues.
• Re-enable voicemail — dial 1750 from your O2 handset to reactivate the voicemail service.
• Contact O2 — call 202 from your O2 phone (free) or 0344 809 0202 from another phone.

Can I disable O2 voicemail and stop calls going to 901?

Yes. If you would prefer that unanswered calls ring out rather than divert to the voicemail number O2 uses, you can deactivate voicemail by dialling 1760 from your O2 handset. To reactivate it later, dial 1750. Business users who want calls to route to a VoIP system instead should use the conditional call-forwarding codes outlined above.

Does the voicemail number O2 uses work on giffgaff?

Yes. giffgaff operates on the O2 network and uses the same voicemail number — 901. Simply dial it from your giffgaff handset to access your mailbox. Tesco Mobile, which also piggybacks on O2's infrastructure, uses a different code: 222.

How do I change my O2 voicemail PIN?

Dial 901 from your O2 phone, then navigate to the settings or mailbox options menu (typically by pressing 3 or 4 depending on the menu version). Select the option to change your PIN and enter a new four-digit code. Alternatively, you can manage your PIN through the My O2 app under your account settings.

Is there a better voicemail option for my business?

If your team regularly misses calls or you need features such as voicemail-to-email, transcription, shared mailboxes, and call routing, a hosted VoIP system will significantly outperform the standard voicemail number O2 offers. You can keep your O2 SIMs and simply forward unanswered calls to a VoIP platform. Get a free quote from Connection Technologies to see how it works for your setup.