> 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/t1-e1-and-j1-interfaces.md).

# T1, E1, and J1 interfaces

The Tmedia [TMG3200](https://telcobridges.com/media-gateways/products/tmedia-gateways/tmg3200/) and Tdev [TMP6400](https://telcobridges.com/products/development-platforms-tdev/tmp6400-tdev-voip-gateway-development-platform/) TDM hardware adapters for T1, E1, and J1 lines provide for up to 64 lines. It is important that you verify the TDM module installed in your Tmedia unit.

For each T1/E1/J1 line that the Tmedia unit will use, a line interface with a related line service is configured in a one-to-one relationship. The configuring of the line interface activates the hardware and the line service is configured to transport traffic and signaling payload. A conceptual image is shown below:

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

### Using BITS ports for signaling

Starting with release 2.3 of [Toolpack](https://telcobridges.com/products/development-platforms-tdev/), it is possible to convert unused BITS ports into [signaling ports](https://github.com/telcobridges-main/tmedia-wiki/tree/main/reference/transmission/signaling-ports/README.md), with indices of 1 and 0 respectively, in order to recover a channel on the primary STM-1 connection. However, the converted ports will be used as trunks, and not as clocking sources.


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