> 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/ss7-backward-call-indicator.md).

# SS7 Backward Call Indicator

The Backward Call Indicator (BCI) signals information about the call setup to the call originator. You have, for example, the "Charge Indicator" which indicated if a call should be charged.

It is a 16 bits field (see Q.763, section 3.5) value passed in the ACM and/or the ANM.

### TelcoBridges and BCI

The TelcoBridges platforms can insert or override the default values sent for the BCI. This is configured in the [profiles](https://github.com/telcobridges-main/tmedia-wiki/tree/main/tmedia/configuration/creating-profiles/README.md).

Default value for this field is described in Hexadecimal with bits in this order: (HG-FE-DC-BA-PO-N-M-L-K-J-I)

Default value for this field is Hexadecimal **0x5404** (01-01-01-00-00-0-0-0-1-0-0) as seen in the table.

| Bits name | Bit#  | Name                              | default value | Meaning                                   |
| --------- | ----- | --------------------------------- | ------------- | ----------------------------------------- |
| HG        | 15-14 | End-to-end method indicator       | 01            | pass-along method available               |
| FE        | 13-12 | Called party's category indicator | 01            | ordinary subscriber                       |
| DC        | 11-10 | Called party's status indicator   | 01            | subscriber free                           |
| BA        | 9-8   | Charge indicator                  | 00            | no indication                             |
| PO        | 7-6   | SCCP method indicator             | 00            | no indication                             |
| N         | 5     | Echo Control Device indicator     | 0             | incoming echo control device not included |
| M         | 4     | ISDN access indicator             | 0             | terminating access non-ISDN               |
| L         | 3     | Holding indicator                 | 0             | holding not requested                     |
| K         | 2     | ISDN user part indicator          | 1             | ISDN user part used all the way           |
| J         | 1     | End-to-end information indicator  | 0             | no end-to-end information available       |
| I         | 0     | Interworking indicator            | 0             | no interworking encountered               |

The default value can be overridden with a mask **Default backward call indicator enforce mask**. All mask bits with 0 will take the default value. All mask bits with 1 will override with the **Default backward call indicator**.

The configuration allows to send the BCI in the ANM (SS7 answer) in addition to sending it in the ACM (SS7 Address complete). Use the option **Force backward call indicator in ANM**.

The BCI value can also be modified in the [Routing Scripts](https://github.com/telcobridges-main/tmedia-wiki/tree/main/reference/api/routing-script-tutorial-development-guide/README.md)

### Related actions

**Refer to the appropriate Toolpack release:**

* [Modify TDM SS7 profile](https://github.com/telcobridges-main/tmedia-wiki/tree/main/reference/signalling/modifying-tdm-ss7-profile-settings/README.md)

### References

* Q.763 Signaling System No.7 - ISDN user part format and codes, section 3.5


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