Detecting Collect Calls

The device detects collect calls (reverse charge calls) using any of the following information elements (IE) in the received Q.931 ISDN Setup message for Tel-to-IP calls:

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Reverse Charging Indication IE

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Facility IE

When the device detects a collect call, it adds a proprietary header (X-Siemens-Call-Type: collect call) to the outgoing SIP INVITE message.

No special configuration is required for the feature.