Short answer: Boost Mobile Australia says your number expires if you do not recharge the service for six months. Recharge before that deadline and confirm the new expiry in My Boost Mobile.
Open the SIM expiry calculator for a sourced deadline
Use the Boost rule, not a network inference
Boost runs on the Telstra network, but that fact alone does not prove how Boost handles expiry. The primary source for this answer is Boost's own help page, which says the number expires after six months without a recharge.
Telstra's current prepaid terms also cover Boost services and describe a six-month recharge-only period after recharge expiry. They say a Boost customer can access the My Boost Mobile app and Boost recharge page during that period.
What keeps the number active?
Recharge the Boost service before the six-month deadline. Do not substitute an incoming call, a Wi-Fi message, or an assumption that having signal counts as activity. Boost's published answer is based on recharge.
After payment, open My Boost Mobile and verify the next expiry. If your app shows a specific date, use it instead of converting “six months” into a fixed 180 or 183 days.
What happens after expiry?
Boost's short help article does not promise that an expired number can be recovered. Telstra's prepaid terms say a service that is not recharged during the recharge-only period is disconnected and the number reallocated. Treat the displayed deadline as final.
Compare other Australian prepaid rules, read the number recycling guide, or return to the Australia section.
Record Boost's displayed expiry date
KeepSim can remind you before it. It cannot recharge Boost or recover a number once the carrier has reallocated it.
Get KeepSim on the App StoreOfficial sources
- Boost: How long before my number expires?, reviewed 2026-08-01.
- Telstra Pre-Paid Mobile Service Terms, clauses 2.5–2.7.
- 2026-08-01: replaced network-based inference with Boost's own published rule.
KeepSim is not affiliated with Boost Mobile or Telstra.