Security rules for public SMS inboxes
Plain list of what you should never verify with a shared number — and what is usually OK.
Public inboxes trade privacy for convenience. These rules are non-negotiable on InstantNum.
Never use for
- Banking, crypto, or payment apps
- Password or email recovery
- Government ID or tax services
- Primary social accounts you cannot afford to lose
- Medical or insurance portals
Usually OK for
- Developer test accounts
- One-time coupons or newsletters you will abandon
- Checking whether a foreign signup flow works
- Demos where the data is fake anyway
Assume breach
Anyone can read the inbox. Treat every message as if it were posted to a public forum. If that thought makes you uncomfortable for a given service, use your own number.
More detail in our disclaimer and privacy policy.