10DLC
The US system for registering businesses that send automated texts from standard 10-digit local numbers.
42 terms
Virtual number glossary
The words you meet when you receive SMS online or verify an account, explained in plain English.
1
2
2FA (two-factor authentication)
Signing in with two different proofs, typically a password plus a code, app prompt, passkey or security key.
A
A2P SMS
Application-to-person messaging: texts sent automatically by software, such as verification codes and alerts.
Account takeover
When someone other than the owner gains control of an online account, usually by stealing a password or login code.
Full definition →SIM swapSmishing2FA (two-factor authentication)
Area code
The digits after the country code that indicate a geographic region, like 212 in the US or 20 for London.
Authenticator app
An app that generates time-based login codes on your device, with nothing sent over the phone network.
Full definition →2FA (two-factor authentication)OTP (one-time password)Passkey
B
Backup codes
A set of single-use codes you save when enabling 2FA, to sign in if you lose your phone or second factor.
Full definition →2FA (two-factor authentication)Authenticator appPasskey
Burner number
A second, discardable phone number for calls and texts, usually from a burner or second-line app.
Full definition →Disposable numberVoIP numberTemporary phone number
C
Caller ID
The number, and sometimes a name, displayed on your phone when someone calls you.
Full definition →Sender ID spoofingVoice verificationSmishing
Carrier
A mobile network operator or provider that issues phone numbers and delivers calls and texts.
Country code
The international dialing prefix for a country, such as +1 for the US and Canada or +44 for the UK.
D
Delivery receipt
A status report a carrier sends back to the sender saying whether a text was delivered, failed or expired.
Disposable number
A phone number meant to be used briefly and thrown away, so your personal number stays private.
Full definition →Temporary phone numberBurner numberNumber recycling
E
E.164 format
The international standard way to write a phone number: a plus sign, country code and national number, no spaces.
eSIM
A digital SIM built into your phone that lets you add a mobile line by scanning a QR code or using a carrier app.
H
HLR lookup
A network query that checks whether a mobile number is active and which mobile network currently serves it.
L
Landline number
A fixed-line phone number tied to a home or office connection rather than a mobile phone or SIM.
Full definition →Voice verificationLine type lookupArea code
Line type lookup
A check that tells an app whether a number is mobile, landline or VoIP, and often which carrier owns it.
Long code
A standard full-length phone number, like a regular mobile or 10-digit number, used to send or receive texts.
M
MVNO
A mobile virtual network operator: a phone company that sells service using another carrier's network.
N
Non-VoIP number
A phone number issued by a mobile carrier for a SIM, so line type checks report it as mobile rather than VoIP.
Number porting
Moving your existing phone number from one carrier or provider to another so you keep the same number.
Number recycling
When a phone number that someone stopped using is reassigned to a new subscriber or user.
Full definition →Temporary phone numberDisposable numberCarrier
O
OTP (one-time password)
A short code that is valid for a single login or verification and expires quickly.
P
P2P SMS
Person-to-person messaging: ordinary texts typed and exchanged between individual phone users.
Passkey
A phishing-resistant sign-in credential stored on your device and unlocked with your fingerprint, face or PIN.
Full definition →2FA (two-factor authentication)Authenticator appSmishing
R
Rate limit
A cap on how many codes or attempts a service allows in a period, after which you must wait.
S
Sender ID
The name or number shown as the sender of a text message, such as a short code, a phone number or a brand name.
Sender ID spoofing
Faking the name or number shown as the sender of a text so a scam message looks like it came from a trusted source.
Short code
A 5 or 6 digit number that businesses use to send high-volume texts such as verification codes and alerts.
SIM card
The small chip that identifies your line to a mobile carrier and links your phone to your number.
SIM swap
An attack where someone gets your carrier to move your number to their SIM so they receive your calls and codes.
Full definition →Number porting2FA (two-factor authentication)Authenticator app
Smishing
Phishing by text message: a fake SMS that tries to get you to click a link, share a code or send money.
SMS gateway
A system that lets software send and receive text messages by connecting apps to mobile carrier networks.
SMS verification
Confirming that you control a phone number by entering a code the service texts to it.
Full definition →OTP (one-time password)Rate limitShort code
T
Temporary phone number
A number you use for a short time, often one verification, before it is returned to the provider and reassigned.
Full definition →Disposable numberNumber recyclingSMS verification
Toll-free number
A number that callers can dial at no charge, such as 800 or 888 numbers in North America and 0800 in the UK.
U
USDC on Solana
A US-dollar stablecoin sent over the Solana blockchain, one of the ways to top up a Noir SMS balance.
V
Verification fraud
Abuse of phone or SMS verification systems, such as fake account creation or artificially inflated SMS traffic, that platforms work to stop.
Virtual phone number
A phone number used without a physical SIM in your own phone, reached through an app, website or online dashboard.
Full definition →Temporary phone numberVoIP numberNon-VoIP number
Voice verification
Confirming a phone number by answering an automated call that reads you a one-time code.
Full definition →SMS verificationLandline numberOTP (one-time password)
VoIP number
A phone number that runs over the internet rather than a mobile carrier's SIM, such as Google Voice or TextNow lines.
Full definition →Non-VoIP numberLine type lookupVirtual phone number
From definitions to your code
Private temporary numbers for SMS verification. Refund if no SMS arrives.