> 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/protocols/isdn.md).

# ISDN

Integrated Systems Digital Network (ISDN) is a circuit-switched telephone system that integrated voice and data on the same lines.

### TelcoBridges and ISDN

Tmedia and Tdev systems can be configured to provide an ISDN signalling stack on the trunks of one or more units to meet system configuration requirements. ISDN signaling stacks are signaling resources that are assigned to a specific line of the Tmedia or Tdev unit. Based on the [Q.931](http://en.wikipedia.org/wiki/Q.931) switch variant that will be used by the system, a selection of ISDN variants are available. For each line service requiring ISDN signaling, an ISDN signaling stack is created with its own distinct signaling variant.

![ISDN signaling stacks](https://docs.telcobridges.com/w/images/4/43/ISDN_signaling_stacks.jpg)

Note: The trunks of each Tmedia or Tdev unit can be configured to have their own ISDN signaling stack.

### Configuration

**Refer to the appropriate Toolpack release:**

| Tmedia/Tsig/Tdev                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| \*[Web Portal v3.2: ISDN Signaling](https://github.com/telcobridges-main/tmedia-wiki/tree/main/tmedia/configuration/tmedia-tdev-and-tsig-web-portal-protocol-stacks/README.md#isdn-fas-and-nfas) \*[Web Portal v3.0: ISDN Signaling](https://github.com/telcobridges-main/tmedia-wiki/tree/main/tmedia/configuration/tmedia-tdev-and-tsig-web-portal-3-0-protocol-stacks/README.md#isdn-fas-and-nfas) \*[Web Portal v2.10: ISDN Signaling](https://github.com/telcobridges-main/tmedia-wiki/tree/main/tmedia/configuration/tmedia-tdev-and-tsig-web-portal-2-10-protocol-stacks/README.md#isdn-fas-and-nfas) \*[Web Portal v2.9: ISDN Signaling](https://github.com/telcobridges-main/tmedia-wiki/tree/main/tmedia/configuration/web-portal-2-9-protocol-stacks/README.md#isdn-fas-and-nfas) \*[Web Portal v2.8: ISDN Signaling](https://github.com/telcobridges-main/tmedia-wiki/tree/main/tmedia/configuration/web-portal-2-8-protocol-stacks/README.md#isdn-fas-and-nfas) |

### References

* [Wikipedia article](http://en.wikipedia.org/wiki/Integrated_Services_Digital_Network)
* [Supported ISDN standards and variants](https://github.com/telcobridges-main/tmedia-wiki/tree/main/reference/protocols/isdn-specification/README.md)


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