> 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/mtp2-specification.md).

# MTP2 Specification

TelcoBridges' implementation of the [MTP2](https://github.com/telcobridges-main/tmedia-wiki/tree/main/reference/protocols/mtp2/README.md) software conforms to the following standards:

* GR-246, Issue 3, T1.111.3 SS7 Signaling Data Link (MTP Level 2), ANSI 1992.
* Q.701 SS7 (MTP), CCITT 1992.
* Q.703 SS7 Signaling Data Link, CCITT 1992.
* JT-Q.703 MTP Signaling Link, TTC recommendation (\*)
* NTT - Q.703 MTP Specifications, NTT recommendation (\*)

(\*) Available only through the TB640 native API as those are not currently supported by layers above (MTP3, M3UA, etc) in the complete Toolpack framework.

The following messages may be received or transmitted by MTP2 across the line interfaces / line services:

* Message Signal Unit (MSU)
* Link Status Signal Unit (LSSU)
* Fill-In Signal Unit (FISU)

### Variants

The following protocol variants are supported:

**MTP2**

* ITU (< ITU BLUE > used for ITU88)
* ITU92( < ITU WHITE > used for ITU92, ITU97, Q767, SINGAPORE and CHINA)
* ANSI88 (used for ANSI88)
* ANSI92 (used for ANSI92, ANSI96 and TELCORDIA)

**MTP3**

* ITU = (88, 92, 97, Q767 and SINGAPORE)
* CHINA
* ANSI = (88 and 92)
* ANSI 96 = (96 and TELCORDIA)

**ISUP**

* ITU = (88 and 92)
* ITU 97
* SINGAPORE
* ANSI 88
* ANSI 92
* ANSI 95
* TELCORDIA 97
* CHINA
* UK
* ETSI
* ETSIV3

#### Protocol variant compatibility

| MTP2    | MTP3    | ISUP                |
| ------- | ------- | ------------------- |
| ITU 88  | ITU     | ITU                 |
| ITU 88  | ITU     | ITU 97              |
| ITU 88  | ITU     | Singapore           |
| ITU 88  | ITU     | Q767                |
| ITU 88  | ITU     | United Kingdom (UK) |
| ITU 88  | ITU     | ETSI                |
| ITU 88  | ITU     | ETSIv3              |
| ITU 88  | China   | China               |
| ITU 92  | ITU     | ITU                 |
| ITU 92  | ITU     | ITU 97              |
| ITU 92  | ITU     | Singapore           |
| ITU 92  | ITU     | Q767                |
| ITU 92  | ITU     | United Kingdom (UK) |
| ITU 92  | ITU     | ETSI                |
| ITU 92  | ITU     | ETSIv3              |
| ITU 92  | China   | China               |
| ANSI 88 | ANSI    | ANSI 88             |
| ANSI 88 | ANSI    | ANSI 92             |
| ANSI 88 | ANSI    | ANSI 95             |
| ANSI 88 | ANSI    | Telcordia           |
| ANSI 88 | ANSI 96 | ANSI 88             |
| ANSI 88 | ANSI 96 | ANSI 92             |
| ANSI 88 | ANSI 96 | ANSI 95             |
| ANSI 88 | ANSI 96 | Telcordia           |
| ANSI 92 | ANSI    | ANSI 88             |
| ANSI 92 | ANSI    | ANSI 92             |
| ANSI 92 | ANSI    | ANSI 95             |
| ANSI 92 | ANSI    | Telcordia           |
| ANSI 92 | ANSI 96 | ANSI 88             |
| ANSI 92 | ANSI 96 | ANSI 92             |
| ANSI 92 | ANSI 96 | ANSI 95             |
| ANSI 92 | ANSI 96 | Telcordia           |


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