# &adminguide;

## Overview

Module for updating ISUP encapuslated in SIP (SIP-T/SIP-I)

The sipt module can be used to update various ss7 headers contained inside a message.

## Dependencies

The module depends on the following modules (in the other words the listed modules must be loaded before this module):

- none

## Functions

### `sipt_destination(destination, hops, nai)`

updates the IAM in the body if it exists, setting the called party number to destination with the nature address specified in nai and decrementing the hop counter value if present. If the hop counter header is missing it will be added with the value of hops.

#### `sipt_destination(destination, hops, nai)` usage

    ...
    # update the destination number to our current request uri,
    # setting nature of address to international
    $rU = "19495551234";
    sipt_destination($rU, 31, 4);
    ...

### `sipt_set_calling(origin, nai, presentation, screening)`

updates the IAM in the body if it exists, setting (or adding) the calling party number to origin with the nature address specified in nai and setting the presentation and screening values to presentation and screening.

#### `sipt_set_calling(origin, nai, presentation, screening)` usage

    ...
    # update the calling party to the value in the from header
    sipt_set_calling($fU, 4, 0, 3);
    ...

## Exported pseudo-variables

### `$sipt_presentation`

Returns the value of the Address presentation restricted indicator contained in the Calling Party Number header of the IAM message if it exists. Returns -1 if there isn't a Calling Party Number header.

#### Address Presentation Restricted Indicator Values

0 | presentation allowed
1 | presentation restricted
2 | address not avail (national use)
3 | spare

#### `sipt_presentation pseudo-variable` usage

    ...
    # add privacy header if restriction is requested
    if($sipt_presentation == 1)
    {
    	append_hf("Privacy: id\r\n");
    	$fn = "Anonymous";
    }

    ...

### `$sipt_screening`

Returns the value of the Screening Indicator contained in the Calling Party Number header of the IAM message if it exists. Returns -1 if there isn't a Calling Party Number header.

#### Screening Indicator Values

0 | Reserved (user provided, not verified)
1 | User Provided, Verified and Passed
2 | Reserved (user provided, verified and failed)
3 | Network provided

#### `sipt_screening pseudo-variable` usage

    ...

    # remove P-Asserted-Identity header if the screening isn't verified
    # or network provided
    $avp(s:screening) = $sipt_screening;
    if($avp(s:screening) != 1 && $avp(s:screening) != 3)
    {
    	remove_hf("P-Asserted-Id");
    }

    ...

### `$sipt_hop_counter`

Returns the value of the Hop Counter for the IAM message if it exists. Returns -1 if there isn't a hop counter.

#### `sipt_hop_counter pseudo-variable` usage

    ...
    # get the hop counter and update the Max-Forwards header if it exists
    $avp(s:hop) = $sipt_hop_counter;
    if($avp(s:hop) > 0)
    {
    	remove_hf("Max-Forwards");
    	append_hf("Max-Forwards: $avp(s:hop)\r\n");
    }

    ...

### `$sipt_cpc`

Returns the value of the Calling Party Category for the IAM message. Returns -1 if there is a parsing error.

#### `sipt_cpc pseudo-variable` usage

    ...
    # get the Cpc code and set put it in a custom sip header
    append_hf("X-CPC: $sipt_cpc\r\n");

    ...

### `$sipt_calling_party_nai`

Returns the value of the Nature of Address Indicator of the Calling Party for the IAM message. Returns -1 if there is a parsing error or if the Calling Party Number is not present.

#### Calling Nature of Address Values

0 | Spare
1 | Subscriber Number (national use)
2 | Unknown (national use)
3 | National (significant) number (national use)
4 | International use

#### `sipt_calling_party_nai pseudo-variable` usage

    ...
    # get the Calling Nai and add country code if national
    if($sipt_calling_party_nai == 3)
    {
    	$fU = "32" + "$fU";
    }

    ...

### `$sipt_called_party_nai`

Returns the value of the Nature of Address Indicator of the Called Party for the IAM message. Returns -1 if there is a parsing error.

#### Called Nature of Address Values

0 | Spare
1 | Subscriber Number (national use)
2 | Unknown (national use)
3 | National (significant) number
4 | International use
5 | Network-specific number (national use)

#### `sipt_called_party_nai pseudo-variable` usage

    ...
    # get the Called Nai and add country code if national
    if($sipt_called_party_nai == 3)
    {
    	$rU = "32" + "$rU";
    }

    ...