A glossary of the most common terms in business SMS messaging: message types, delivery codes, security and technical concepts that appear in the guides on our blog. We will keep expanding it with every new article.
A
A2P (Application-to-Person)
Messaging sent by a system or application to a person, such as OTP codes, alerts or order confirmations. It is the type of traffic business platforms handle, as opposed to P2P (person-to-person). Learn more in what A2P SMS is and how it differs from P2P.
Agentic AI
Artificial intelligence systems that, beyond answering questions, carry out multi-step tasks on their own: they query systems, complete a request and notify the customer of the result. In customer service they often rely on SMS to confirm and update. More in agentic AI in customer service.
Alphanumeric sender ID
A text identifier (up to 11 characters, such as a brand name) shown as the SMS sender instead of a phone number. It reinforces brand identity, although recipients cannot reply to it. Learn more in alphanumeric sender, short code or long number.
API (SMS API / REST API)
An interface that lets your own system send and receive SMS programmatically, with no manual work. A REST API uses standard HTTP, which makes it easy to integrate with almost any language or platform. Learn more in the SMS API integration guide for Mexico. See also the SMS API for Mexico.
API token (Bearer Token)
The credential that identifies your system to the API and is sent in the Authorization header of every request. It must be stored on the server, never in a mobile app or the browser. Learn more in the SMS API integration guide.
B
Blacklist
A list of numbers that should not receive messages, either because they opted out or because they generate recurring delivery errors. Keeping it up to date improves your sending reputation.
Bulk SMS
Sending the same message, usually personalized, to many recipients at once from a platform: campaigns, notices or reminders. Learn more in bulk SMS for businesses in Mexico.
C
CAMARA (open network APIs)
Open-source project of the Linux Foundation, developed together with the GSMA, that defines standard APIs for mobile operators to expose network functions such as Number Verification or SIM swap checks. It is the technical basis of the Open Gateway initiative. See how they combine with OTP in MFA: SMS OTP vs authenticator app vs push.
Cell Broadcast (emergency alerts)
Technology that sends the same message to every phone connected to certain cell towers in an area, without knowing their numbers. It is used for emergency alerts, such as earthquake alerts on mobile phones. Unlike business SMS, it cannot personalize the message per recipient or provide delivery reports.
Class 0 message
The technical name for Flash SMS: a message shown directly on the phone screen that, by default, is not saved in the inbox. Learn more in flash SMS: what it is and how to turn it off.
CNBV (National Banking and Securities Commission)
The body that regulates Mexico’s financial system, including which authentication factors banks and fintechs may use for digital operations, among them SMS with an OTP code. Learn more in the CNBV allows SMS authentication codes.
CONDUSEF
Mexico’s National Commission for the Protection and Defense of Financial Services Users. It receives complaints from banking users and publishes fraud alerts, including those that arrive by SMS (smishing). Learn more in smishing in Mexico: 2026 figures.
Content encryption (RSA-OAEP)
Protection of the destination number and the message text before they are sent to the API, so they travel encrypted on top of HTTPS. It is used when content is sensitive, as in banking or healthcare. Learn more about the SMS API for Mexico.
CPaaS (Communications Platform as a Service)
A cloud platform that offers communication capabilities —SMS, voice and other messaging channels— through APIs, so companies can build them into their applications without running their own telecom infrastructure. Learn more about enterprise SMS messaging.
CRT (Telecommunications Regulatory Commission)
Mexico’s telecommunications regulator, successor to the IFT (Federal Telecommunications Institute). Among other initiatives, it is preparing regulation against SMS spam and unsolicited calls.
CSAT (Customer Satisfaction Score)
Satisfaction metric that measures the percentage of customers who rate an experience positively, for example 4 or 5 on a 1-to-5 scale. It can be measured with a short question sent by SMS right after a purchase or service interaction. See SMS message examples and templates.
CURP (mobile line registration)
A process that links every mobile line in Mexico to its owner’s CURP (national ID code). Lines that do not complete the registration within the deadline for their ending digit are suspended: since September 2026 millions of lines have already been suspended, and deadlines run until December 31. An OTP or alert sent to a suspended line is not delivered, so it pays to review delivery reports and clean your databases. Learn more in CURP phone registration: impact on SMS and OTP.
D
Deliverability
The percentage of sent messages that actually reach the recipient. It depends on factors such as number quality, the line’s CURP registration, message content and sender reputation. Learn more in why an SMS is not delivered.
Delivery latency
The time between your system sending the message and the phone receiving it. It is critical for OTP codes: if the code is slow, the user gives up or requests another. Learn more in why an SMS is not delivered.
Delivery rate
The percentage of messages that reached the phone out of the total sent, according to delivery reports (DLR). It is the main indicator for evaluating a campaign or a provider. See delivery reports (DLR) in real time.
Delivery statuses (DELIVRD, UNDELIV, EXPIRED, REJECTD)
Standard codes that indicate the final result of an SMS in its delivery report: DELIVRD (delivered), UNDELIV (undeliverable, for example because the number does not exist or is inactive), EXPIRED (the validity period ran out before delivery, as when the phone is off) and REJECTD (rejected before delivery was attempted). Learn more in delivery reports (DLR) in real time.
DLR (delivery report)
The confirmation returned by the mobile network indicating whether an SMS was delivered, failed or is still in transit. It is the basis for measuring deliverability by campaign, by carrier or by individual message. Learn more in how to receive delivery reports (DLR) in real time.
Double opt-in
A two-step way to record consent: the customer subscribes and then confirms, for example by replying to an SMS or opening a link. It leaves clear evidence of authorization to receive promotional messages. See the requirements for commercial SMS in Mexico.
E
ESME (External Short Message Entity)
In the SMPP protocol, the external application or platform that connects to a message center to send SMS and receive delivery reports and inbound messages. Learn more about the SMPP connection.
F
Fallback (backup channel)
A strategy that sends the message through a second channel when the first one fails or does not confirm delivery; for example, an OTP by SMS when the app notification does not arrive, or a voice call when the SMS is not delivered. Learn more in SMS as a critical channel for banking and fintech.
Flash SMS
A message that appears directly on the phone screen without opening the inbox, and is not saved by default. It is used for urgent notices meant to be read immediately. Learn more in flash SMS: what it is.
G
GSM-7 encoding
The standard 7-bit encoding for SMS, which allows up to 160 characters per segment. It only supports the basic GSM alphabet; an accent or character outside it can force a different encoding. See how many characters an SMS has.
GSMA Open Gateway
Initiative of the GSMA, the global association of mobile operators, for operators to offer common network APIs to developers and businesses, for example to verify numbers or detect a recent SIM change. It uses the specifications of the CAMARA project.
H
HLR (Home Location Register)
The mobile network database that holds each number’s subscription information. An HLR lookup tells you whether a line exists, whether it is active and which network it belongs to, which helps clean databases before a send.
I
IFT (Federal Telecommunications Institute) — now CRT
It was Mexico’s telecommunications regulator until its functions passed to the CRT (Telecommunications Regulatory Commission), which now sets the sector’s rules, including messaging guidelines and the proposal against SMS spam and unsolicited calls.
L
LFPDPPP (Mexico’s Federal Law on the Protection of Personal Data Held by Private Parties)
Mexican law that regulates how companies collect, use and protect personal data, including the mobile numbers in their contact lists. It requires a privacy notice and a clear purpose for each use of the data. A new version of the law was published in 2025. See the requirements for marketing SMS in Mexico.
Link shortener (short URL)
A service that turns a long web address into a short one so it takes up fewer characters in the SMS. Use your own or a recognizable domain: generic shorteners are widely used in fraud and can reduce trust or trigger filters.
Long code
A standard-format phone number (similar to a mobile number) used as an SMS sender. It is usually preferred when one-to-one two-way messaging is needed. Learn more in which type of sender to use.
M
MFA (multi-factor authentication)
A security scheme that combines two or more factors to verify identity (something you know, something you have, something you are). SMS OTP is one of the most used factors because of its reach and simplicity. Learn more in MFA: SMS OTP, authenticator app or push notification.
MO (Mobile Originated)
A message that originates on the user’s phone and travels to the business platform or system, such as a reply to a two-way SMS.
MSISDN
The full phone number of a mobile line in international format, with country code (for example, 52 55 1234 5678). It identifies the recipient in messaging platforms and is usually written in E.164 format.
MT (Mobile Terminated)
A message that originates on the business platform and ends on the user’s phone. It is the direction most A2P traffic travels: OTPs, alerts and campaigns.
N
NPS (Net Promoter Score)
Loyalty metric that asks, on a 0-to-10 scale, how likely the customer is to recommend the company. It is calculated by subtracting the percentage of detractors (0 to 6) from the percentage of promoters (9 and 10). A one-question SMS survey usually gets a good response rate.
Number portability
A user’s right to keep their number when switching phone companies. That is why a number’s prefix is not enough to know which carrier it belongs to today, something to keep in mind when analyzing reports by carrier.
Number Verification
Network API, defined in CAMARA, that confirms whether the number a user claims matches the SIM in the phone connected to the mobile network, without sending a code. It complements SMS OTP, which remains the universal method because it works on any phone.
O
Opt-in / Opt-out
Opt-in is a contact’s explicit consent to receive commercial messages. Opt-out is the mechanism to unsubscribe (for example, by replying “STOP”). Both are required to send commercial SMS legally in Mexico. Learn more in what you need to send commercial SMS.
OTP (One-Time Password)
A single-use code, valid for a limited time, used to verify identity at login, sign-up or during a transaction. See how SMS OTP authentication works and SMS OTP for authentication and verification.
P
P2P (Person-to-Person)
Messaging sent between two people, such as SMS between personal phones. It differs from A2P traffic, which is what businesses handle. Learn more in differences between A2P and P2P SMS.
Passkey
A passwordless authentication method based on the FIDO2 standard: the device stores a cryptographic key unlocked with a fingerprint, face or PIN. Banks are adopting it as a complement to OTP; SMS remains key for customer onboarding, account recovery and notifications. Learn more in two-factor authentication methods.
Personalization variables (merge fields)
Fields replaced in each message with the recipient’s data, such as name, appointment date or amount due. They let you send bulk SMS that read like individual messages. See how to send bulk SMS from Excel or CSV.
Phishing
Fraud that tries to steal personal or financial data by impersonating a trusted entity, usually by email. When it is done by SMS it is called smishing. Learn more in what smishing is and how to protect your customers.
PNN (National Numbering Plan)
The reference that defines how phone numbers are assigned in Mexico and which type of service, landline or mobile, each range belongs to. At Grupo Tecnophone we check every number against the PNN before sending to detect landlines that cannot receive SMS and avoid unnecessary costs.
Preventive collections
Reminders sent before a payment’s due date to reduce delinquency. SMS is one of the most effective channels for this because of its high read rate. Learn more in debt collection messages by SMS: examples and rules. Templates in payment reminder SMS.
Privacy notice (aviso de privacidad)
A mandatory document in Mexico that tells data subjects how their personal data will be used. Sending commercial SMS requires having made it available to the recipient along with obtaining their consent. Learn more about regulation and consent for commercial SMS.
Promotional SMS
A message for marketing or advertising purposes (offers, discounts, campaigns). Unlike transactional SMS, it requires the recipient’s prior consent and an opt-out mechanism. Learn more in transactional vs. promotional SMS.
R
RCS (Rich Communication Services)
A standard promoted by the GSMA to modernize phones’ native messaging with images, buttons, read receipts and interaction. It requires a compatible device, app and network, so SMS remains the backup channel.
RCS Business Messaging (RBM)
The business version of RCS that lets a brand send rich messages —cards, carousels, buttons and suggested replies— from a verified sender profile, in the phone’s native messaging app.
REPEP (Public Registry to Avoid Advertising)
A registry run by PROFECO (Mexico’s consumer protection agency) where people can ask not to receive advertising calls or messages. Promotional campaigns must respect it; transactional and security messages are a different category. Learn more in the SMS anti-spam rules the CRT is preparing.
S
Sandbox (test environment)
An API environment that validates credentials, IP, format and encryption just like production, but without delivering real messages. It lets you integrate and test at no cost. See the developer guides.
Sender ID
The identification the recipient sees as the message’s origin: it can be a long code, a short code or an alphanumeric ID. The choice affects recipient trust and whether the message accepts replies. Learn more in SMS sender types.
Sender mask (máscara)
The term used in Mexico for an alphanumeric sender ID: the SMS arrives with the brand name instead of a number. See alphanumeric sender ID: meaning and examples.
Sending window
The range of days and hours in which messages are scheduled. Critical notices, such as an OTP, are sent at any time; promotions are best sent during daytime hours and respecting the customer’s consent.
Short code
A number with only a few digits used to send and receive SMS, common in bulk campaigns and subscription services. It allows higher sending volume than a long code. Learn more in which type of sender to use.
SIM swap
Fraud in which a criminal gets the victim’s number transferred to a new SIM to receive their SMS and OTP codes. It is mitigated with identity checks when replacing a SIM, SIM-change alerts and additional factors for high-risk operations. Learn more in how to choose an authentication method.
Smishing
Phishing by SMS: fraudulent messages that impersonate a bank, courier or institution to steal data or money. It is different from a legitimate transactional SMS, even though both arrive through the same channel. Learn more in smishing in Mexico: 2026 figures and how to protect your customers.
SMPP (Short Message Peer-to-Peer)
The industry-standard protocol for exchanging high volumes of SMS between platforms. It is an alternative to the REST API when higher throughput or low-level control is needed. Learn more about the SMPP connection and the full journey of an SMS.
SMS firewall
A system carriers use to inspect SMS traffic entering their network and block unauthorized or fraudulent messages, or those sent through disallowed routes. For businesses, it means sending through authorized channels and with content that cannot be mistaken for fraud.
SMS gateway
A platform that connects a company’s systems to the messaging network to send and receive SMS, usually through an API or the SMPP protocol. We explain it in what an SMS gateway is and in the SMS API integration guide.
SMS pumping (artificially inflated traffic)
Fraud in which bots trigger OTP or other SMS requests to numbers controlled by the attacker in order to profit from that traffic. It is prevented with per-number and per-IP limits, anti-bot checks on forms and monitoring of anomalous patterns. Learn more in how SMS OTP works.
SMS segment (concatenation)
Each block of up to 153 or 67 characters (depending on encoding) into which a message longer than a single SMS is split. Segments are sent separately and reassembled on the phone as one message, but each one is billed separately. Learn more in how many characters an SMS has.
SMSC (Short Message Service Center)
The network element that receives, stores and forwards SMS to the recipient. If the phone is unavailable, it retries delivery until the message’s validity period expires.
T
Throughput
The number of messages per second a platform can send. It is a key factor when you need to deliver an OTP or a mass alert in the shortest possible time. Learn more in the bulk SMS guide for Mexico.
TPS (transactions per second)
A measure of an SMS connection’s sending capacity: how many messages per second it can transmit. It is also expressed as MPS. In SMPP it depends on the number of sessions and the window of pending messages. Learn more about the SMPP connection.
Tracking link
A link included in an SMS that records who clicked and when, to measure each campaign’s response. It should use a domain the customer recognizes so it doesn’t reduce trust.
Transactional SMS
A message the recipient expects because it is part of a process they started: an OTP code, a purchase confirmation, a delivery notice. It has no advertising purpose. Learn more in what a transactional SMS is and transactional SMS for businesses.
Two-factor authentication (2FA)
An access method that requires two factors from different categories: something the user knows (a password), something they have (their phone) or something they are (their fingerprint or face). An OTP code sent by SMS is one of the most widespread ways to implement the second factor. Learn more about SMS OTP.
Two-way SMS
A mode in which the recipient can reply to the SMS (for example, answering “YES” to confirm an appointment) and the reply is received back in the sender’s platform or system. Learn more in two-way SMS: how to use your customers’ replies.
U
UCS-2 encoding
The 16-bit encoding required when a message includes characters outside the GSM-7 alphabet (emojis, or certain accents and symbols). It lowers the limit to 70 characters per segment.
V
Verification code
A single-use number, usually 4 to 8 digits, that a company sends by SMS to confirm that the person logging in or making a transaction is the owner of the line. It is the most common use of OTP. Learn more in what an OTP is and how it works.
Vishing
Fraud equivalent to phishing but carried out by phone call, usually impersonating a bank or institution to obtain data or verification codes.
Voice call OTP
A variant of OTP in which the code is read out in an automated call. It is used as a backup when the SMS does not arrive, or for users with landlines or who have difficulty reading the message.
W
Webhook
An automatic notification one system sends to another in real time when an event occurs, such as a delivery report (DLR) or an inbound SMS (MO), without the receiving system having to ask for it. Learn more in what a webhook is and how to receive DLRs.
Whitelist
A list of explicitly authorized numbers or senders, used to ensure that certain critical messages (such as a bank OTP) are not blocked by anti-spam filters.
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