Cisco SRP521W-K9-G1 Administration Guide - Page 111

Configuring Voice Configuring Dial Plans 6 STEP 3 Scroll down to the Control Timer Values section. STEP 4 Enter the desired values in the Interdigit Long Timer field and the Interdigit Short Timer field. Refer to the definitions at the beginning of this section. Secure Call Implementation This section describes secure call implementation with the SRP. It includes the following sections: • Enabling Secure Calls • Secure Call Details • Using a Mini-Certificate • Generating a Mini Certificate NOTE This is an advanced topic only meant for experienced installers. Enabling Secure Calls A secure call is established in two stages. The first stage is no different from normal call setup. The second stage starts after the call is established in the normal way with both sides ready to stream RTP packets. In the second stage, the two parties exchange information to determine if the current call can switch over to the secure mode. The information is transported by base64 encoding embedded in the message body of SIP INFO requests, and responses using a proprietary format. If the second stage is successful, the SRP plays a special Secure Call Indication Tone for a short time to indicate to both parties that the call is secured and that RTP traffic in both directions is being encrypted. If the user has a phone that supports Call Waiting Caller ID (CIDCW) and that service is enabled, the CID will be updated with the information extracted from the Mini-Certificate received from the remote party. The Name field of the CID will be prepended with a '$' symbol. Both parties can verify the name and number to ensure the identity of the remote party. Cisco SRP500 Series Services Ready Platforms Administration Guide (SRP520 Models) 111