A unique ID (identification) is assigned to each subscriber. This is typically the public DID number of the subscriber if the subscriber is reachable via DID. However, the subscriber ID need not be a number that is dialable from the PSTN.
Each subscriber BGL is given a subscriber ID, which is the E.164 number assigned to this endpoint. In the US, this is typically the 10 or 11-digit PSTN number of the endpoint (for example 15619231001). Even if it is not callable from the public network, it must have such a service or subscriber ID. If a BGL is not callable from the public network, it will be marked in such a way that its subscriber ID will not be reported to the public network as a caller ID, since it is not a valid caller ID. Instead, a substitute number, such as departmental main number, will be transmitted, or the caller ID can be signaled as unavailable.
The network designer has the option of defining subscriber IDs with or without the country code:
If the country code is included in the subscriber ID—for example, 15619231000— the number type is by definition “international.”
If the country code is not included in the subscriber ID—for example, 5619231000— the number type is “national.”
If a Lotus Sametime Unified Telephony is serving subscribers in a single country, inclusion of the country code is optional. If the Lotus Sametime Unified Telephony system is serving subscribers in more than one country, including the country code eliminates potential number ambiguities.
Lotus Sametime Unified Telephony recommends defining subscriber identities in the international form, with the country code as part of the subscriber ID (for example, 1-561-923-1234). In a private network involving multiple switches, the subscriber numbering plan needs to be consistent network-wide.
Through the subsequent numbering plan configuration steps, the administrator can make it possible to reach this endpoint through any of the standard dialing forms:
Extension number (31001)
Location code plus extension number (923-1001 or abc-1001)
Private network barrier code plus location code plus extension number (8- abc-1001)
Full PSTN number (with or without the country code)
However, the identity of the subscriber is defined by the Subscriber ID (also known as the Service ID [E.164 number]), and that identity must be unique within the system. Two subscribers (in different BGs) may have the same extension number without any confusion, but two subscribers cannot have the same Service ID (E.164 number) even if they are in different BGs or on different Lotus Sametime Unified Telephony switches.
Lotus Sametime Unified Telephony supports the concept of subscriber groups (within a business group) being physically scattered in locations (sites) that are physically remote from the Lotus Sametime Unified Telephony system, in different time zones, or even across national borders. For this reason, a BG can have more than one numbering plan.
Each subscriber within a BG may be assigned to a specific numbering plan, which overrides the default (common) numbering plan assigned to the BG itself. This provides the preferred mechanism for the definition of site-specific dialing routing, when all the subscribers at multiple sites are within one BG.
If the administrator decides that a BG should have only one numbering and routing plan, the unique routing requirements of a specific site can also be accomplished by using routing area and class of service assignments.
Parent topic: Numbering Plan