Depending on the country and operator, multiple options exist for the Transmission Path Originating Address (TPOA) setting, also known as the “From” field on the handset. Operators often use the TPOA as a means to regulate MT delivery to their subscribers.
Typically in countries where only the sender pays for messaging, there are few if any TPOA restrictions. At the other end of the spectrum, in countries where both the sender and the recipient pay (for example, the US and Canada), operators require a registered short code that adheres to a sometimes exhaustive list of requirements. Most of the world however falls somewhere in the middle.
The other use for long codes and short codes is to permit two-way messages with the subscriber. Short codes are country-specific while long codes can be country-specific (National long code) or supported in multiple countries (International long code).
Note: For specific country availability and restrictions, refer to our SMS Country Guidelines documents and for other countries check with your Account Manager.