Glossary
SMS (Short Message Service)
SMS, or Short Message Service, is the cellular carrier protocol for sending text messages up to 160 characters between mobile handsets without requiring a data connection or a dedicated app.
General definition
SMS was standardised as part of GSM in 1985 and remains one of the most universally reachable communication channels. A message travels from the sender’s carrier through the SS7 signalling network to the recipient’s carrier and then to the handset. No internet connection is required, only a cellular signal.
- Near-universal delivery across all mobile phones worldwide
- No app installation required by the recipient
- 160-character limit per segment (longer messages split into multiple segments)
- No native encryption, read receipts, typing indicators, or rich media beyond MMS
SMS is widely used for one-time passwords (OTP), transactional alerts, and appointment reminders. It is not suitable for ongoing conversation, team messaging, or rich-media workflows. RCS is the intended successor, adding richer features to the native texting experience. Branded in-app messaging provides even greater control for product builders.
In the Ethora ecosystem
Ethora is not an SMS provider. Ethora’s Chat SDK lets you embed a fully owned, branded messaging experience inside your product, with read receipts, file sharing, AI agents, and group rooms that SMS cannot support. Users stay inside your app rather than switching to a carrier messaging thread.
For regulated industries such as healthcare and finance, in-app chat via Ethora provides end-to-end encryption and audit logging that SMS, as an unencrypted carrier protocol, cannot guarantee. SMS can still be used as a secondary notification or OTP channel alongside the primary in-app experience.
