Type of Number

The Type of Number (TON) is additional information that in some signaling systems can be sent together with a number to, or over a public or private network.

The TON is always affiliated to either a called, calling, or connected number. It is a way to categorize the level of the number in a network, for example, as international, national or local. This categorization is always related to from where in the network the number is seen.

The MX-ONE™ system handles 5 types of public numbers, TON = 0-4, and 3 types of private numbers, TON = 5-7. TON is stated for both the calling and for the called number. The TON for calling or connected number is actually two TONs, one is affiliated to the public number and one is affiliated to the private number.

• TON for called number 0-7
• TON for calling number
  • TON for public calling number 0-4
  • TON for private calling number 5-7
• TON for connected number
  • TON for public connected number 0-4
  • TON for private connected number 5-7

The TON for called number is mainly used for not having to send the national and international prefix to the public exchange. Instead, the TON for the called number (sent together with the called number) is set to international or national. The public exchange will know from the TON instead of from the national or international prefix that it is a national or international type of number.

The TON for the called number is re-set in every transit exchange as the call passes exchanges on its way to the destination. This means that the setting of this TON only have to consider the situation in the closest following exchange.

The TONs for calling number (public and private) is used to control the composing of a complete calling or connected number (public and private) to send to the inter-working exchange or public network. These TONs are first used to compose complete calling numbers (public and private) to send to the terminating exchange. After this, they are sent together with the calling number through the network, and in the terminating exchange they are used to control the composing of the complete connected numbers (public and private) to send back to the originating exchange. Lastly, these TONs are sent back as TONs for connected number with the connected numbers.

In an hierarchic numbering plan, the TON for calling number is mandatory information.

The proprietary TON used by the includes both Type of number and Numbering Plan Identifier (NPI) as specified in the ISDN standards. The TON used by the MX-ONE Service Node is a subset of the possible settings in ISDN. When sent to an ISDN the TON is transformed into a proper ISDN TON and NPI. See Figure 2 for more information on the support for TON in different signaling systems and configurations.

Note: The handling of NPI unknown in ASP113 is controlled by an O&M parameter (TL60, VARC). The default behavior is for a received number with NPI unknown to be set as ASP113’s TON “unknown public”.