Last reviewed: June 2026 | Source: Ofcom and Three UK
TL;DR- Three UK is a mobile network operator owned by CK Hutchison.
- Customers can reach Three by calling 333 from a Three phone or on a published customer service number.
- Three publishes a coverage checker so customers can see expected signal at an address.
- Unresolved complaints can be taken to an Ofcom-approved alternative dispute resolution scheme after eight weeks or a deadlock letter.
- Switching away uses a PAC code to keep your number, and a notice period normally applies.
Key Facts
●Network owner: CK Hutchison
●Customer service from a Three phone: Dial 333
●Regulator: Ofcom
●Complaint escalation: ADR scheme after 8 weeks or a deadlock letter
●Keep your number: Request a PAC code by texting PAC to 65075
●Notice period: Typically 30 days when leaving
Three UK is one of the country's mobile network operators, and like all providers it is bound by Ofcom rules covering complaints, switching and keeping customers informed. Whether the issue is a billing query, poor signal or a desire to move to another network, there are set routes to follow. This guide explains how to contact Three, how to check coverage, how the complaints and dispute resolution process works, and the steps to switch away while keeping your number.
Who owns Three UK
Three UK is a mobile network operator owned by CK Hutchison, the Hong Kong-based conglomerate, and it has operated in the UK since the early days of third-generation mobile networks. It runs its own network infrastructure and sells contracts, pay-as-you-go plans and broadband products under the Three brand.
As a licensed mobile operator, Three is regulated by Ofcom, which sets rules on issues such as complaints handling, contract information, switching and the treatment of customers. These rules apply to Three in the same way as to the other major networks.
Three has also been the subject of significant industry developments, including a proposed combination with another major UK operator that fell under competition scrutiny. Customers do not need to follow the corporate detail to use the standard service and complaint routes, which are set by regulation.
How to contact Three customer service
The quickest way for most customers to reach Three is to dial 333 free from a Three mobile, which connects to customer service. Three also publishes a customer service telephone number for those calling from another phone, along with online chat and account management through the Three website and app.
For account queries, billing questions and technical problems, the app and online account allow customers to check usage, view bills and manage their plan without calling. Many routine issues can be handled this way, which can be faster than waiting on the phone.
When contacting Three about a problem, it helps to have the account details and any relevant reference numbers ready, and to keep a note of who was spoken to and when. Keeping a record is useful if the issue is not resolved and needs to be escalated as a formal complaint.
Checking network coverage
Three provides an online coverage checker that lets customers enter a postcode or address to see the expected level of signal for calls, texts and mobile data, including any planned improvements or known issues in the area. Checking coverage is sensible before taking out a contract, because mobile signal varies significantly by location.
Coverage checkers show predicted signal rather than a guarantee, since actual reception can be affected by buildings, terrain and network congestion. Customers experiencing poor signal at home or work can use the checker to confirm whether the issue matches the expected coverage or points to a fault.
If signal is much worse than the checker predicts, this can support a complaint or, in some cases, a right to leave a contract, depending on the circumstances and the consumer protections that apply. Documenting the problem and the coverage prediction strengthens any such case.
How to make a complaint
Three has a published complaints procedure, and the first step is to raise the issue directly through its customer service channels, giving the company the chance to put things right. Complaints can usually be made by phone, online or in writing, and Three should acknowledge and investigate the matter.
Ofcom rules require providers to handle complaints fairly and to provide information about how to escalate if the customer is not satisfied. Keeping a clear record of the complaint, including dates and any reference numbers, helps if the matter is not resolved quickly.
If the complaint cannot be resolved, the customer has the right to take it further through an independent dispute resolution scheme, which provides a route to a decision without going to court. The complaint process is designed to give the provider a fair opportunity to resolve the issue before that stage.
Escalating to alternative dispute resolution
If a complaint to Three remains unresolved after eight weeks, or if Three issues a deadlock letter confirming there is nothing more it can do, the customer can take the case to an Ofcom-approved alternative dispute resolution, or ADR, scheme. ADR is independent and free to the consumer, and its decision can be binding on the provider.
ADR schemes consider the evidence from both sides and can order remedies such as an apology, a correction or compensation where appropriate. The customer is not obliged to accept the outcome, but if they do, the provider must comply.
Telecoms providers must belong to an Ofcom-approved ADR scheme, and they must tell customers which scheme covers them. This gives consumers a clear, low-cost route to an independent decision when a complaint cannot be settled directly with Three.
Switching away from Three
To switch to another network while keeping the same phone number, a customer requests a PAC, or Porting Authorisation Code, which can be obtained by texting PAC to 65075. Three must provide the code, and the customer gives it to the new provider, which arranges the transfer, normally within one working day.
A notice period, typically 30 days, may apply, but under Ofcom rules customers are generally not charged for the notice period once the switch using a PAC is complete, so they do not pay twice. Any outstanding handset costs or charges for leaving before the end of a minimum term may still apply.
Customers who want to leave without keeping their number can request a STAC instead, which cancels the service. Checking whether the contract is within its minimum term, and whether any handset balance remains, helps avoid unexpected charges when switching away.
It is also worth reviewing whether any add-ons, insurance or international bolt-ons are attached to the account, because these can continue or need cancelling separately. Where a contract bundles a handset and airtime together, the airtime portion can sometimes end while payments for the device continue until the phone is paid off, so understanding how the contract is structured helps a customer plan a clean switch without paying for a service they no longer use.
Frequently Asked Questions
How do I contact Three customer service?
The quickest way is to dial 333 free from a Three mobile, which connects you to customer service. Three also publishes a customer service number for calls from other phones, along with online chat and account management through its website and app. Many routine queries, such as checking usage and bills, can be handled in the app without calling, which is often faster than waiting on the phone.
How do I check Three coverage at my address?
Three provides an online coverage checker where you enter a postcode or address to see the expected signal for calls, texts and data, along with any known issues or planned improvements. The checker shows predicted coverage rather than a guarantee, because reception can be affected by buildings, terrain and congestion. Checking before you take out a contract is sensible, as mobile signal varies significantly by location.
How do I complain about Three and escalate?
First raise the issue through Three's customer service so it has a chance to resolve it, keeping a record of dates and reference numbers. If the complaint is unresolved after eight weeks, or Three issues a deadlock letter, you can take it to an independent Ofcom-approved alternative dispute resolution scheme, which is free to you and can order remedies. Three must tell you which ADR scheme covers your complaint.
How do I switch away from Three and keep my number?
To keep your number, text PAC to 65075 to request a Porting Authorisation Code, then give that code to your new provider, which arranges the transfer, normally within one working day. A notice period, typically 30 days, may apply, but under Ofcom rules you generally will not be charged for it once the switch is complete. Any outstanding handset costs or early exit charges may still apply.
