Digital encryption can reduce the risk of intercepting phone conversations, voice mail, and the signaling messages that support them both. A digital phone call consists of voice (bearer) data and call signaling (control) messages. Both bearer and signaling data can pass through many devices and networks, sometimes over a separate network or virtual path from each other. Without encrypting both data types anyone with access could intercept:
Digitized voice signals in phone calls and voice mail
Call signaling messages that:
Setup, maintain, and tear down calls
Contain call duration
Reveal the callers’ names and numbers
Transmit encryption keys
Translation (administration) data in transit or saved on a storage device include IP addresses and routing information from which an attacker can analyze traffic patterns.
Configuration data through TLS connections
Application-specific traffic
Data exchanged during management and administration sessions
The table compares how encryption mitigates the vulnerabilities in signaling and bearer media.
Table 1. Comparisons in signaling and bearer traffic| Media
|
Unencrypted (cleartext)
|
Encrypted
|
|---|
| Bearer
|
Vulnerable to eavesdropping
|
Prevents eavesdropping
|
| Signaling
|
Susceptible to message spoofing and registration hijacking
|
Prevents message spoofing and hides sensitive information
|