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Error Handling Rules

If a call cannot be handled normally due to an error (e.g. failure to find a value for a mandatory tag), the application can be configured to behave differently depending on the available information for the call. Rules are applied in the order listed until a match is made.

Once matched, various actions can be taken: release the call, play an announcement, etc. If a rule does not specify any matching criteria, it will always match; this should only be used as a catch-all.

Configuration Details

Each rule can support the following attributes:

| Attribute | Type | Description | | :-------: | :--: | :---------- | | `action` | String | **[Required]** The action to take when this rule is matched. Possible values are shown under [Error Handling Rule Actions](#error-handling-rule-actions). | | `tag` | String | **[Conditional]** The [tag](/config/dsg_scp/diameter/tags.html) name to match the value for If `tag` is present, `value` must also be present. | | `tag_x` | String | **[Conditional]** As for `tag`, but with `x` representing a unique pairing, e.g. `tag_1` or `tag_a`. A matching `value_x` must also be present. | | `value` | (various) | **[Conditional]** The string or integer value to match against during rule selection. Required when `tag` is present. | | `value_x` | (various) | **[Conditional]** As for `value`, but with `x` representing a unique pairing, e.g. `value_1` or `value_a`. A matching `tag_x` must also be present. | | `originating` | Boolean | Whether this rule applies for [MO calls](/applications/dsg_scp.html#traffic-type-determination).
(Default: `true`) | | `forwarding` | Boolean | Whether this rule applies for [MF calls](/applications/dsg_scp.html#traffic-type-determination).
(Default: `true`) | | `terminating` | Boolean | Whether this rule applies for [MT calls](/applications/dsg_scp.html#traffic-type-determination).
(Default: `true`) | | `at_initial` | Boolean | Whether this rule applies at the initial OCS interrogation, i.e. the Diameter `CC-Request-Type` is `1` (`INITIAL_REQUEST`).
(Default: true) | | `at_update` | Boolean | Whether this rule applies at interim OCS interrogations, i.e. the Diameter `CC-Request-Type` is `2` (`UPDATE_REQUEST`). Note that [some actions](#error-handling-rule-actions) are not applicable at interim interrogation.
(Default: as for [Error Handling Rule Actions → Valid At](#error-handling-rule-actions)) | | `at_terminate` | Boolean | Whether this rule applies at the final OCS interrogation, i.e. the Diameter `CC-Request-Type` is `3` (`TERMINATE_REQUEST`). Note that [some actions](#error-handling-rule-actions) are not applicable at final interrogation.
(Default: as for [Error Handling Rule Actions → Valid At](#error-handling-rule-actions))) | | `cause` | Integer | The release cause to send to the network if the `action` releases the call.
(Default: 31) | | `announcement_id` | Integer | **[Required with `action` = `announcement_release` or `announcement_connect`]** The announcement ID to play to the caller, if appropriate to the `action`. | | `srp_name` | Integer | **[Required with `action` = `announcement_release` or `announcement_connect`]** The SRP name (as configured in the `ScpApp`) to use to play an announcement to the caller, if appropriate to the `action`. | | `divert_to` | String | **[Required with `action` = `connect` or `announcement_connect`]** The normalised destination digits to connect the call to, if approrpiate to the `action`. | | (other available fields) | (various) | Any number of selector rule [available fields](/config/dsg_scp/diameter/selector_rules.html#available-fields). |

Error Handling Rule Actions

Each error handling rule allows the specification of a single action to take when an error condition is encountered during processing.

Note that if the calling party is no longer present in the call (i.e. they have hung up or been disconnected), no action will be able to be applied.

The following actions are available:

Action	Required Parameters	Optional Parameters	Valid At	Description
`release`	-	`cause`	(all)	Release the call immediately with the given `cause`.
`connect`	`divert_to`	-	`initial`	Terminate the call to the provided `divert_to` with no further rating interaction.
`announcement_release`	`announcement_id` `srp_name`	`cause`	(all)	Play announcement ID `announcement_id` on the resource `srp_name` (as configured under SRP Endpoints) and then apply handling as for `release`.
`announcement_connect`	`announcement_id` `srp_name` `divert_to`	-	`initial`	Play announcement ID `announcement_id` on the resource `srp_name` (as configured under SRP Endpoints) and then apply handling as for `connect`.
`abort`	-	-	(all)	Send a `TC_ABORT` to end the call immediately.

Default Error Handling Actions

The below default rules are always applied after all configured error handling action rules to act as a fallback. They may not be disabled, but earlier rules will be used in preference (including rules with no selectors which will always be chosen as fallbacks):

<error_handling>
    <rule action="release" />
</error_handling>