Glossary SMS verification, term by term.
30 short, plain-language definitions of the vocabulary behind phone verification: numbers, routes, codes, and checks.
- A2P SMS Application-to-person SMS: messages sent by software (verification codes, alerts) rather than by another person.
- Activation window The time a rented number stays allocated to you and listening for the verification SMS, typically 5-20 minutes.
- Country calling code The 1-3 digit prefix that routes a number to its country: +1 for the US and Canada, +49 for Germany, +81 for Japan.
- Delivery report (DLR) The carrier's confirmation that an SMS reached the destination handset, or an error explaining why it did not.
- Disposable number A number intended to be abandoned after brief use, especially the free public numbers shown on receive-SMS websites.
- E.164 The international standard format for phone numbers: plus sign, country code, subscriber number, no spaces, max 15 digits.
- Flash call Verification by a brief incoming call where the last digits of the calling number are the code, so the call never needs answering.
- Gray route An unofficial SMS delivery path that dodges carrier A2P fees, cheaper but heavily filtered and unreliable.
- HLR lookup A live query to a carrier's Home Location Register that reveals whether a mobile number is active and which network it belongs to.
- KYC (know your customer) Identity verification that regulated services must perform, typically a government ID check plus a selfie.
- Long code A standard-length phone number used for SMS; what you actually rent when you buy a verification number.
- Mobile network operator (MNO) A company that owns mobile network infrastructure and issues phone numbers from its allocated ranges, like Vodafone or T-Mobile.
- MVNO A mobile virtual network operator: a carrier that sells service under its own brand using another operator's physical network.
- Non-VoIP number A phone number from a real mobile carrier range, as opposed to one issued by an internet telephony provider.
- Number activation One rental of a number for one verification: the number is allocated, receives the code, and returns to the pool.
- Number pooling Recycling numbers through a shared pool: after an activation ends, the number rests and later serves another customer for a different service.
- OTP (one-time password) A short code valid for a single login or verification, typically 4-8 digits delivered by SMS, voice call, or generated by an app.
- P2P SMS Person-to-person SMS: ordinary texting between two individual subscribers.
- Phone number reputation A platform's internal risk score for a phone number, based on its range, history, and how many accounts it has verified.
- Sender ID The name or number an SMS appears to come from, such as "Google" or a short code, instead of an ordinary phone number.
- Short code A 4-6 digit number used by businesses to send high-volume SMS like verification codes; can send but not receive like a normal number.
- SIM farm Hardware holding hundreds of SIM cards to send or receive SMS in bulk; a major source of supply and abuse in the SMS market.
- SMS gateway The system that moves messages between the internet and carrier networks, connecting applications to the SMS world.
- SMS verification Confirming that a user controls a phone number by sending a one-time code by SMS and asking them to type it back.
- Temporary phone number A number used for a short period, from minutes (one verification) to weeks (a rental), then returned to the pool.
- TOTP (time-based one-time password) A one-time code generated on your device from a shared secret and the current time, used by authenticator apps like Google Authenticator.
- Two-factor authentication (2FA) Requiring a second proof of identity beyond the password, such as an SMS code, an authenticator app, or a hardware key.
- Virtual phone number A real phone number used without a physical SIM card in your device, typically rented briefly to receive an SMS verification code.
- Voice OTP A one-time code read out in an automated phone call instead of delivered by SMS.
- VoIP number A number issued by an internet telephony service rather than a mobile carrier; often blocked for SMS verification.
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