Secure Call Implementation; Enabling Secure Calls - Cisco SR520-FE-K9 Administration Manual

Configuring Voice
Configuring Dial Plans
STEP 3
STEP 4
NOTE
Cisco SRP500 Series Services Ready Platforms Administration Guide (SRP520 Models)
Scroll down to the Control Timer Values section.
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
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.
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