> 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/mtp1-layer.md).

# MTP1 Layer

The MTP1 layer is the physical SS7 layer and is responsible for the [HDLC](https://github.com/telcobridges-main/tmedia-wiki/tree/main/reference/protocols/hdlc/README.md) framing of [SS7](https://telcobridges.com/media-gateways/solutions/signaling/migrating-ss7-sigtran/) packets (usually called MSU – Message signaling unit). Besides the transmission and reception of frames and the calculation of CRC, this layer is also responsible for monitoring and reporting the quality of the link based on the number of failures detected (CRC errors, unexpected packets). Using specially formatted packets (LSSU and FISU), this layer ensures that the communication with the peer side is always valid and synchronized, even when the communication link is supposedly idle (no MSU being sent).

### TelcoBridges and MTP1

TelcoBridges supports MTP1 as part of its SS7 signaling stack.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://prosbcdocs.telcobridges.com/telecom-references/protocols/mtp1-layer.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.