> For the complete documentation index, see [llms.txt](https://prosbcdocs.telcobridges.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://prosbcdocs.telcobridges.com/telecom-references/transmission-and-lines/line-interface.md).

# Line Interface

Line interface is a generic term for TDM physical interfaces. TelcoBridges products support 3 types of physical interfaces (available in 4 varieties of [TDM module options](https://prosbcdocs.telcobridges.com/tmedia-documentation/products/tmedia/installation/tdm-module-options)):

* [T1/E1/J1 interfaces](/telecom-references/transmission-and-lines/t1-e1-and-j1-interfaces.md)
* [DS3 interfaces](/telecom-references/transmission-and-lines/ds3-interfaces.md)
* [SONET/SDH interfaces](/telecom-references/transmission-and-lines/sonet-sdh-interfaces.md)

Toolpack requires that each line interface contains at least 1 [line service](/telecom-references/transmission-and-lines/line-service.md).

### Example

For RJ48 TDM interfaces, configuring a connector as a T1 line interface requires that a T1 [line service](/telecom-references/transmission-and-lines/line-service.md) be added (see picture below).

![T1 e1 j1 line interfaces](https://docs.telcobridges.com/w/images/d/d9/T1-e1-j1-line-interfaces.jpg)

For a BNC connector, configuring it as a DS3 line interface requires that a DS3 [line service](/telecom-references/transmission-and-lines/line-service.md) be added, followed by either up to 28 T1/J1 or up to 21 E1 [line services](/telecom-references/transmission-and-lines/line-service.md)(see picture below).

![Schematic DS3 interfaces](https://docs.telcobridges.com/w/images/6/6f/Schematic-DS3-interfaces.jpg)


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