Short answer: On Three UK, your number is at risk after 180 days with no chargeable activity. The number is lost and you'd need a brand-new SIM.
How long you have on Three UK
That Three UK SIM you forgot about can stop being yours sooner than you'd think. On Three UK, the number is at risk after 180 days with no chargeable activity. Three is strict: there is no recovery once a PAYG number is disconnected.
A working SIM that still shows signal doesn't mean the number is still yours — on prepaid, the number is tied to activity, not to whether the card powers on. (See what happens when you stop using a prepaid SIM for the full lifecycle.)
Can you get your Three UK number back?
None — Three states a disconnected PAYG number can't be reconnected. The number is lost and you'd need a brand-new SIM. Once a number has been released to the pool and reassigned to someone else, it's gone for good.
What counts as keeping it active
For almost every carrier the rule is the same: it has to be something they bill — an outgoing call or SMS, paid mobile data, or a top-up or paid add-on. Internet apps like WhatsApp, iMessage and FaceTime run over data and usually don't count, and incoming calls and voicemail often don't either. The cheapest way to stay active is one small billable action before the deadline — more in how to keep a prepaid SIM active without spending money.
Comparing carriers? See the full prepaid expiration policies table for the US, UK, Australia and Canada.
Don't lose your Three UK number by accident
KeepSim gives this line its own countdown, warns you on your Home Screen before the deadline, and lets you fire a keep-alive action in one tap. Local-first, no account.
Get KeepSim on the App StoreCommon questions
How long before Three UK recycles your number?
On Three UK, your number is at risk after 180 days with no chargeable activity. The number is lost and you'd need a brand-new SIM.
Can you get your Three UK number back?
None — Three states a disconnected PAYG number can't be reconnected. Once the number has been released and reassigned, getting it back is almost never possible.
Does using WhatsApp keep the number active?
Usually no. WhatsApp, iMessage and similar apps run over data or Wi-Fi and don't count as carrier activity. You typically need a billable call, text, paid data, or a top-up.
Last verified June 2026 against Three UK official support. Carrier policies change often and depend on your exact plan and country — treat this as a starting point, not legal advice, and confirm the current rule with Three UK before relying on it. KeepSim is a personal reminder tool; it does not provide telecom service or keep numbers active on your behalf.