---
title: "Two-way SMS"
description: "Two-way SMS lets a business both send messages (mobile-terminated, MT) and receive replies (mobile-originated, MO) from customers, using a short code or long code that can accept inbound texts."
canonical: "https://omnichannels.ai/glossary/two-way-sms/"
language: "en"
updated: "2026-10-10"
publisher: "BroadNet Technologies"
brand: "OmniChannels.ai"
---

# Two-way SMS

Canonical: https://omnichannels.ai/glossary/two-way-sms/
Language: en
Publisher: OmniChannels.ai by BroadNet Technologies

**Definition:** Two-way SMS lets a business both send messages (mobile-terminated, MT) and receive replies (mobile-originated, MO) from customers, using a short code or long code that can accept inbound texts.

Outbound messages are MT; replies are MO. The provider receives MO messages from the operator and forwards them to the business via a webhook, an inbox or, on SMPP, as deliver_sm PDUs.

Typical uses are appointment confirmations (reply YES/NO), customer support threads, surveys, keyword opt-ins and STOP handling for opt-out.

Two-way SMS requires a reply-capable sender. Alphanumeric sender IDs cannot receive replies, so two-way flows use short codes or virtual long codes, subject to availability in each country.

Design tips: tell people what to reply, acknowledge every reply, process STOP immediately and route anything the automation cannot handle to a human agent.

## Example

```
Your appointment is on 14 Oct at 10:30. Reply 1 to confirm or 2 to reschedule.
```

## Sources

- [SMPP Protocol Specification v3.4 (Issue 1.2) — SMPP.org](https://smpp.org/SMPP_v3_4_Issue1_2.pdf)