Lotus Sametime Unified Telephony supports modification of presentation numbers. All numbers which are sent out by the Lotus Sametime Unified Telephony are provided either by Translation or by Display Number Modification. Display Number Modification is responsible to provide all numbers which are used for presentation purposes (e.g. calling number, alerting number, connected number, forwarding number).
Presentation Numbers and Dialed Numbers
can be calling party numbers, connected party numbers, busy party numbers, alerting party numbers, etc. The only other numbers Lotus Sametime Unified Telephony supports next to the presentation numbers are called party numbers. Called party numbers (or also dialed numbers) are the number strings that are dialed by a user in order to reach another user.
may be of implicit nature (means that the type of number dialed is conveyed in prefixes pre-pended to the called party's number) or explicit nature (means that the type of number dialed is already known through some other means).
A dialed number string becomes a 'dialable number' string only after Lotus Sametime Unified Telephony's translation engine determined that the dialed number string leads to a valid destination be it a Home DN or an external user in a private or public network.
Use of Display Number Modification
The purpose of number modification is to present received presentation numbers in 'dialable' format to the partner of the call. Per definition when a party receives a dialable number, that dialable number can be used as the dialed string when the called party wants to call the calling party.
Figure 1. Dialable Number
Presenting numbers in dialable format is especially useful for call logs and journals, but it just makes sense to display numbers in a consistent way to users and most users would expect to see a dialable number on their display.
Another use for number modification is for applications and gateways that expect normalized numbers. This normalization can be seen as a special case of creating a dialable number as the application or gateway would expect to receive all dialable numbers in normalized format. Per definition a normalized number of the E164 numbering scheme is an international number. The normalization level of a number of a private numbering scheme depends on what type of private numbering scheme is in effect, but the normalized number is always the highest level number that is applicable in the private numbering scheme (L2, L1 or L0).
The CSTA interface provided by Lotus Sametime Unified Telephony uses normalized numbers as device identifiers. Because it only transports implicit numbers, it sends all normalized numbers of the public numbering scheme in Global Number Format (GNF). A GNF number is an international public number preceded by a '+'.
Public Numbering Scheme
It defines 3 types of numbers
subscriber numbersFigure 2. Public (E.164) Numbering scheme
Within the public numbering scheme, the country code is mandatory. For each country a national authority may define whether it supports:
national numbers and local numbers
only national numbers
only subscriber numbers
Private Numbering Scheme
It defines 3 types of numbers
Local numbersFigure 3. Private Numbering Scheme
Structure of Numbers
Depending upon the customer's wishes, 3 kinds of private numbering schemes can be distinguished:
L0 private numbering scheme: no L1 or L2 level numbers exist in this type of numbering scheme. Normalized numbers are L0 numbers
L1 private numbering scheme: no L2 level numbers exist in this type of numbering scheme. Normalized numbers are L1 numbers.
L2 private numbering scheme: Normalized numbers are L2 numbers
A private numbering scheme administrator should define an L1 code for each L2 private numbering scheme number. This means that for an L2 private numbering scheme, all numbers within the private numbering scheme must have an L2 code and an L1 code defined. Equally so, for an L1 private numbering scheme, all numbers within the private numbering scheme must have an L1 code defined.
Lotus Sametime Unified Telephony supports dialing numbers for subscribers that are shorter than the numbers defined within the public or the private numbering schemes. These short numbers are called extensions and they must be the trailing part of either the subscriber number (public numbering scheme) or the local number (private numbering scheme).
Because most telephones use implicit dialing, the telephone user must indicate which type of number he/she is dialing by possibly entering a prefix before dialing a number out of a numbering scheme.
The prefixes for the public numbering scheme are defined by the operator providing access to the public network. Typically operators do not require dialing a prefix for subscriber numbers, but do require dialing a national prefix for national numbers and an international prefix for international numbers. E.g. the American public network operators chose '1' as the national prefix and '011' as the international prefix, while the German public network operators chose '0' as the national prefix and '00' as the international prefix.
The prefixes for the private numbering scheme are defined by the private numbering scheme administrator. Because extensions are usually seen as the lowest level in a private numbering scheme (although it is not really defined there), prefixes are possible on L0, L1 and L2 level numbers.
Network Access Codes
Network access codes are used within Lotus Sametime Unified Telephony to allow telephone users that dial implicit numbers to differentiate between calls made to the public network and calls made within their own private network.
Parent topic: Display Number Modification