Sending a No-Charge Notification to the Ingress Call Leg

Using a combination of configuration options on both the SBC and PSX, you can configure your network to send a "no-charge" notification back to the ingress leg of a call setup based on criteria you specify.

The SBC provides a trunk group configuration option you can enable to send the URI from the P-Asserted-Identity header in INVITE requests in policy requests to the PSX. The URI is then available for use in configuring PSX selection criteria.

Using options in the PSX Call Parameter Filter Profile, you can define criteria that select calls based on the calling subscriber SIP-URI domain name or the called subscriber's SIP URI domain name. The PSX Policy Profile provides a boolean option (Send P-K-Info) which the PSX returns in its policy response as an indication when a call matched your specified criteria. Refer to the following PSX documentation for more information on the PSX options that are required to implement this feature:

• Policy Profile Screen
• Call Parameter Filter Profile Screen

When the SBC receives an indication in the PSX policy response that the call matched the PSX criteria, it includes a P-K-info:nchg header in its first 18x response towards the ingress leg. This handling occurs unless the initial INVITE request included indications of call-forwarding, such as History-Info headers.

When the SBC includes a P-K-info:nchg header in the 18x response it logs this action in CDR Start and Stop records. Refer to SIP Variant Sub-field Descriptions for more information.

SBC Configuration

To enable this feature, you must enable a signaling parameter on ingress SIP trunk groups to have the SBC send the URI from the P-Asserted-Identity header to the PSX in a policy request. The following is the command syntax for this option:

% set addressContext <AC> zone <zone> sipTrunkGroup <TG NAME> signaling sendPaiUriToPsx <disabled | enabled>

Configuration Example

Use the following commands to enable sending the URI from the P-Asserted-Identity header in a policy request to the PSX for calls from a trunk group called TG_ING.

% set addressContext default zone ZONE1 sipTrunkGroup TG_ING signaling sendPaiUriToPsx enabled
% commit