The world of SMS can be a complicated, jargon-filled place. While we do our best to keep things simple in the Gateway API documentation, sometimes it's much more practical to talk in technical terms. Below you will find a list of the most commonly used, industry-wide terminology and acronyms along with an explanation of what they can mean.

Jargon What does it mean?

Short code

A special telephone number used for value-added billing and messaging services. Often they can be easier to remember when compared to a long code (see but they are limited to a single country. For example, your consumers in Australia would not be able to send to your short code in the United Kingdom.

Long code

A telephone number that is not a short code, often looking like a valid mobile phone number containing more than 10 numbers and containing the country dial code so that it available internationally. For example, +447507332007.

Mobile Originated / MO

Typically this refers to an SMS travelling in the direction from the mobile phone to your short code or long code. For example: Marc sent an MO from his phone to 60999.

In some countries consumers are charged by their network for each MO they send to a short code. This is known as MO billing. Normally you can send a free message back to these consumers, too.

You can usually rely on the consumer having being charged once you receive the message on your HTTP responder but there can still be reductions for a number of reasons, such as if the consumers disputes their bill or potential fraud was detected on the short code.

Mobile Terminated / MT

This refers to an SMS travelling towards the consumer's handset. For example, Marc sent an MT to his phone using Gateway. These messages can be free or premium.

When SMS are charged upon delivery to the consumer's handset then this is known as MT billing. Subject to country-specific regulations, you can charge whatever you like for each message though they will have to opt-in via an MO or by entering their details into a website. Further details are available in MyMessageCloud.

MSISDN The  Mobile Station International Subscriber Directory Number is just a complicated way of describing a standardised method of formatting a mobile telephone number. The number should not contain a plus (+) symbol, no leading 0s and should begin with the international dial code. For example, an MSISDN in the United Kingdom could be: 447445566731. The first two digits, 44, refer to the international dial code and are followed by the consumer's mobile number.


  • One In / One Out 
  • MO or MT Billed with a mandatory MT. Both an MO and an MT is required to complete the transaction. 
  • You can not run subscription services with this billing type. 
  • You may ask the user to send in another message to bill up to the intended transactional value (within the confines of the regulations for that country). 
  • Note the difference between an 'MT billed IO country' and an 'MT billed LC country that doesn't allow subscriptions' is that with the former (IO) you could bill `say` 3 times the line value for a service/product with 3 MO messages sent in from the user, with LC it is not possible to bill multiple times to reach a higher transaction amount.


  • The transaction is limited to a single tariff. In some cases subscription services can be possible with approval, however each MT can only be delivered at the price point of the line. 
  • You are not able to charge higher amounts by sending two or more billed messages or by requesting the user to send in again to increase the value of the transaction. To understand "increase the value of the transaction", this means that within the regulations for that country you can have users re-text for a different service via the same keywords, but you must be delivering back a different product, password, image, ringtone, game, info message, etc.


  • There is an initial, non-billed confirmation request. 
  • The consumer sends a message at standard rate. They receive a non-billed response explaining how much they will be charged. You will need pre-paid bulk credits on your account. The consumer sends a second message at standard rate to confirm the transaction. The outgoing message or messages are at premium rate. 


  • Non-billed incoming messages only.


  • MO billed with billed MT. 
  • Users are billed both for sending in a message, and also for receiving a message, creating a double charge. Non-billed incoming messages only.