# SMS Glossary | VeloBotix

> Definitions: SMS gateway, SMS API, OTP, Sender ID, DLR, Unicode — for Sri Lankan messaging.

Source: https://www.velobotix.app/resources/glossary

# SMS glossary

SMS gateway

A service that connects your application or portal to mobile network operators so SMS can be sent and tracked.

SMS API

A programmatic HTTP interface (at VeloBotix, REST with Basic Auth) to send SMS and check balance.

OTP SMS

A one-time password delivered by SMS for login or verification. The app generates the code; the gateway delivers it.

Transactional SMS

Event-driven messages such as orders, bookings and account alerts — not marketing blasts.

Bulk SMS

One-to-many campaigns, often from CSV or a contact list, with optional personalization.

Sender ID

The name or number shown as the sender. Brand names (alphanumeric) must be registered with operators.

DLR

Delivery report / receipt indicating whether the operator accepted or delivered the message.

Unicode SMS

Messages with Sinhala, Tamil or emoji. They use a shorter character limit per credit than GSM-7 English.

See also [SMS gateway](https://www.velobotix.app/sms-gateway-sri-lanka).