TON/NPI

TON (Type of Number) and NPI (Numbering Plan Identification) are parameters that are used to define the format of a telephone number and the numbering system to which it belongs. These parameters play a key role in telecommunication systems, especially when transmitting messages via SMS or voice calls. Proper TON/NPI configuration helps carriers and routing systems to correctly process and deliver messages, ensuring compatibility between different networks and platforms.

A TON specifies the type of number that is used for addressing. It can be a national, international, short code, or special service number. NPI defines the numbering plan by which the number is constructed, allowing systems to correctly interpret the structure of the number and determine its purpose.

TON/NPI Examples

Suppose you have the number +1 202 555 0173. Here, “+1” is the international country code, “202” is the national area or city code, and “555 0173” - is the local number of the subscriber. In this case, for this number, the TON will be set as “International Number” (International Number) and the NPI will be set as “ITU-T E.164” (the numbering plan that is used for international telephone numbers).

Another example is a short code that is used for SMS campaigns. Let's say the number to send messages is 12345. This number does not follow the normal phone number formats and in order to route it correctly, the TON would be set to “Short Code” and the NPI could be “Private Numbering Plan” to indicate a private numbering plan.

TON Values

TON (Type of Number) categorizes the type of telephone number. The basic values of TON include:

1. Unknown. Used when the type of number is not defined. Often used in situations where the system itself determines the number type.
2. International Number. Indicates that the number begins with the international country code. Example: +44 7911 123456.
3. National Number. This is a number that begins with the national area code or city code without the international code. Example: 020 7946 0958 for London.
4. Network-Specific Number. This type of number is used for specific networks or services, such as corporate networks.
5. Subscriber Number. This is a local subscriber number without a country or area code. Example: 555 0173.
6. Alphanumeric Number. Used for alphanumeric numbers such as SMS sender names.
7. Abbreviated Number. Short numbers used for special services such as short codes for SMS.

NPI values

NPI (Numbering Plan Identification) identifies the numbering plan that is used to interpret a number. Basic NPI values include:

1. Unknown (Unknown). Used when the numbering plan is not defined. This value allows the system to select an appropriate plan on its own.
2. ISDN/Telephone Numbering Plan. This is the most common numbering plan, also known as ITU-T E.164. It is used for most telephone numbers worldwide, including cell phones and fixed phones.
3. Data Numbering Plan. Used for numbers intended for data transmission, such as modems.
4. Telex Numbering Plan. This plan is used for Telex networks, which used to be popular for text-based information.
5. Private Numbering Plan. Used for private networks where numbers may not conform to common standards. Example: corporate telephone systems.
6. National Standard Numbering Plan. This plan is used for numbers that conform to national standards but may differ from international standards.

Properly configured TON/NPI settings ensure that messages and calls are routed correctly, ensuring that they reach their final destination. Understanding the TON and NPI values is especially important for companies that send bulk SMS or provide international services, as it determines the success of interoperability between different networks and platforms.