Service Profile Identifier (SPID)

What is a Service Profile Identifier (SPID)?

In telecommunications, a Service Profile Identifier (SPID) is a number assigned by a phone company to a terminal on an Integrated Services Digital Network (ISDN) B-channel. The SPID identifies each terminal and tells equipment at the phone company's central office about the capabilities of each terminal.

For example, a Basic Rate home or business user may divide service into two B-channels -- or bearer channels -- with one used for telephone voice service and the other for internet data. The SPID tells the phone company whether the terminal accepts voice or data information.

ISDN is a technology that enables the transmission of digital signals -- voice and data -- over telephone copper wires.

ISDN connection

How does SPID work?

Technically, the SPID is a numeric string from three to 20 digits in length. A SPID -- or more than one, if necessary -- is assigned by the carrier network provider when users order the ISDN Basic Rate Interface from the phone company. Beginning in 1998, most phone companies began to use a generic SPID format.

In this format, the SPID is a 14-digit number that starts with the 10-digit telephone number, including area code -- called the directory number -- a two-digit Sharing Terminal Identifier and a two-digit Terminal Identifier. The generic SPID format makes it easier to tell users what to specify when installing an ISDN line and simplifies corporate installation procedures.

As an example, if a line has the telephone number 212-555-1234, the SPID may be 21255512340101.

Most ISDN terminals no longer require the end user to manually enter the SPID. Introduced in 1998, some ISDN manufacturers began to provide non-initializing terminals (NITs) and automated SPID selection in which the correct SPID is automatically downloaded to the terminal from the service provider, rather than having to be specified by the user.

T1 vs. E1 vs. ISDN
The SPID is a number that identifies terminals in the B-channel of ISDN. The B-channel carries the main data, with the B standing for 'bearer' for both levels of ISDN service: the Basic Rate and Primary Rate Interfaces.

Other SPID definitions

In computer databases, the server process ID (SPID or session ID) is an identifier for each connection to the Structured Query Language server. This ID identifies each unique connection and can specify the connection settings. It is synonymous with session or connection.

In Italy, SPID (Sistema Pubblico di Identità Digitale or Public Digital Identity System) is a government-issued digital account that can be used to access digital government and nongovernment services.

This was last updated in September 2021

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