Short answer: There is no standard prepaid expiry rule. Some carriers require recharge, others require chargeable activity, and the starting event may be activation, balance expiry or recharge expiry.
How to read the table
“Timeline” is meaningless without “plan scope”. For example, ALDI's 365-day reset applies after a PAYG recharge, while the initial validity of a newer $5 starter pack can be 60 days. Confidence reflects how directly the current official page supports the summary; it is not a promise that the carrier will never change the rule.
| Carrier | Plan scope | Timeline | What resets it | Confidence | Source / verified |
|---|---|---|---|---|---|
| SoSIM | 香港數據預設組合、其他預設組合及年費組合 | 香港數據預設組合: 120 days; 其他預設組合: 180 days; 年費組合: 365 days | 按官方增值選項增值；延長日數以賬戶顯示為準 | high | SoSIM 香港 常見問題 SoSIM — 取回並重啟已到期號碼 2026-08-01 |
| AT&T Prepaid | AT&T Prepaid accounts with an account-balance expiration date | Payment deadline after balance expiration: 60 days | Make a successful payment before the 60-day cancellation deadline | high | AT&T support 2026-08-01 |
| TIM Pré | Linhas TIM Pré | Cancelamento após vencer a validade da última recarga: 75 days; Prazo máximo para reativar depois do cancelamento: 180 days | Fazer uma recarga de qualquer valor | high | Reativação de linha (TIM oficial) 2026-08-01 |
| Lyca Mobile UK | UK Pay As You Go | No activity; number may be reassigned: 90 days | Complete chargeable carrier activity; confirm the accepted activity with Lyca for your plan | medium | Lyca Mobile UK accessibility policy — unused numbers 2026-08-01 |
| 3HK International Card | 國際萬能卡、社交媒體限定版、內地及港澳台漫遊卡 | 國際萬能卡啟用後: 180 days; 兩款指定版本啟用後: 395 days; 每次增值後: 365 days | 增值；由增值日起延長 365 日 | high | 3HK 國際萬能卡條款及細則（PDF） 2026-08-01 |
| Telstra Pre-Paid | Telstra Pre-Paid Mobile services | Recharge-only period after recharge expiry: 6 months | Recharge during the recharge-only period | high | Telstra Pre-Paid Mobile Service Terms (PDF) 2026-08-01 |
| ALDI Mobile | PAYG Base Plan; starter-pack initial validity varies by activation date | PAYG expiry reset after a PAYG recharge: 365 days; Additional Period after PAYG Base expires: 120 days | Recharge the PAYG service during the Additional Period | high | ALDI Mobile terms (PDF) 2026-08-01 |
| Boost Mobile Australia | Boost Pre-Paid services | No recharge: 6 months | Recharge the Boost service | high | Boost help Telstra Pre-Paid Mobile Service Terms (PDF) 2026-08-01 |
| Three UK | Pay As You Go voice SIM | Chargeable activity required: 180 days | Buy a top-up, Data Pack or Add-on; Make a call, send a text or use mobile data; Use an included allowance on Three's mobile network | high | Three UK official support 2026-08-01 |
| Lebara UK | Pay As You Go services | No chargeable activity; top-up credit is lost: 90 days; Further inactivity before termination: 365 days | Top up or add a plan after the first 90-day period; Perform chargeable activity | high | Lebara UK Terms and Conditions, clauses 13.5–13.6 2026-08-01 |
Patterns that matter
- Recharge-based rules: Telstra, Boost and TIM explicitly anchor protection to recharge.
- Activity-based rules: Three and Lebara name chargeable activity, but their consequences and later windows differ.
- Product-specific rules: SoSIM and 3HK publish different initial validity for different product versions.
- Account date first: AT&T's 60-day deadline begins at balance expiry, so you need the date in the account.
Before acting, open the linked source and your carrier account. The fact registry stores a review date so a future source check can flag stale rows without pretending that every rebuild changed the policy.
For the underlying concepts, read what happens when a prepaid SIM stops being used. If the fact row supports a calculation, use the local SIM expiry calculator.
Turn a verified carrier date into a reminder
KeepSim can store the chosen deadline on your device. It cannot decide which plan you have or complete the required carrier action.
Get KeepSim on the App StoreChange log
- 2026-08-01: replaced the hand-maintained 30-carrier table with rows generated from
content/data/carriers.json; added plan scope, confidence and verification date.
KeepSim is not affiliated with any listed carrier. Links point to carrier or regulator sources and were reviewed on the date shown in each row.