# MO vs MT — what's the difference?

> MT (mobile-terminated) is a message destined for a handset — the operator's network is the destination. MO (mobile-originated) is a message sent from a handset — the operator's network is the source. From an enterprise perspective, every A2P SMS you send is MT, and every reply or inbound keyword (STOP, START, HELP) you receive is MO.

- Canonical URL: https://www.broadnet.me/answers/what-is-mo-vs-mt
- Language: en
- Last reviewed: 2026-07-25
- Publisher: BroadNet (https://www.broadnet.me)

## How MO works in two-way SMS

When a subscriber texts your virtual long number or short code, their operator's SMSC receives an MO submit, looks up the registered destination (your aggregator), and forwards it via SS7 MAP-MO-FORWARD-SHORT-MESSAGE or via SMPP deliver_sm (with esm_class flag indicating MO, not DLR). Your aggregator's gateway delivers it to your webhook.

## Why MO billing differs from MT

MT is billed to the sender (you, the enterprise). MO is billed to the originator (the consumer, on their plan). On premium short codes, MO can be reverse-billed to the consumer at a premium rate that you share in — this is how donation campaigns and premium content monetised in the 2000s. For modern A2P, premium MO is largely dead; standard MO is free to the consumer.

## What MO requires from your aggregator

An inbound virtual number (long number, short code, or alphanumeric two-way capable). Many short codes don't support MO — they are MT-only. Long numbers always do, but consumer recognition is weaker. For two-way conversational use cases see /products/two-way-sms.

## MO in WhatsApp and RCS

The MO/MT terminology is GSM-native. In WhatsApp Business API, the equivalent terms are 'inbound message' (MO-equivalent) and 'outbound message' (MT-equivalent). The semantic is identical; the protocol is HTTP/JSON webhooks instead of SMPP PDUs.

## MO vs MT at a glance

|  | MT (mobile-terminated) | MO (mobile-originated) |
|---|---|---|
| Direction | To the handset | From the handset |
| Enterprise example | Every A2P message you send | Replies, STOP / START / HELP keywords |
| Billed to | The sender (enterprise) | The originator (consumer) |
| Requires | Sender ID + route to destination | Inbound virtual number or short code |
| SMPP carrier | submit_sm | deliver_sm (MO esm_class) |
| WhatsApp / RCS term | Outbound message | Inbound message |

## Frequently asked questions

### Is every A2P message I send MT?

Yes. Application-to-person traffic is destined for a handset, so it is mobile-terminated by definition. The only mobile-originated legs you handle are inbound: replies and keywords from the consumer.

### What is an example of an MO message?

Any inbound message from a subscriber — a reply to your two-way number, or a keyword like STOP, START, or HELP. It originates on the handset and is forwarded to your webhook.

### Who pays for an MO message?

The originator — the consumer, on their own plan. For standard A2P two-way flows the MO is free to the consumer; premium reverse-billed MO (which shared revenue with the brand) is largely obsolete today.

### Do all numbers support MO?

No. Many short codes are MT-only and cannot receive replies; long virtual numbers always support MO. If you need two-way conversation, provision an MO-capable inbound number.

## Related

- [Two-way SMS (product)](https://www.broadnet.me/products/two-way-sms)
- [What is a DLR?](https://www.broadnet.me/answers/what-is-dlr)
- [Short code vs long code](https://www.broadnet.me/answers/what-is-short-code-vs-long-code)
- [All answers](https://www.broadnet.me/answers)
- [What is a DLR (Delivery Receipt)?](https://www.broadnet.me/answers/what-is-dlr)
- [What is A2P SMS?](https://www.broadnet.me/answers/what-is-a2p-sms)
- [What is P2P SMS?](https://www.broadnet.me/answers/what-is-p2p-sms)
- [Two-way SMS](https://www.broadnet.me/products/two-way-sms)