Sip Over Tls - Cisco SPA942 - - IP Phone Administration Manual

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STEP 1
STEP 2
STEP 3
STEP 4
STEP 5
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In addition, the Auth INVITE option for Lines 1 and 2 enables the challenging of
incoming initial SIP INVITE requests.

SIP Over TLS

Transport layer security (TLS) is a standard protocol for securing and
authenticating communications over the Internet.
SIP Over TLS eliminates the possibility of malicious activity by encrypting the SIP
messages by the SIP proxy of the service provider and the end user. SIP Over TLS
relies on the widely-deployed and standardized Transport Layer Security (TLS)
protocol. Note that SIP Over TLS encrypts only the signaling messages and not
the media. A separate secure protocol such as Secure Real-Time Transport
Protocol (SRTP) (see below) can be used to encrypt voice packets.
The TLS protocol has two layers:
• TLS Record Protocol -- layered on top of a reliable transport protocol, such
as SIP or TCH, it ensures that the connection is private by using symmetric
data encryption and it ensures that the connection is reliable.
• TLS Handshake Protocol -- allows authentication between the server and
client and the negotiation of an encryption algorithm and cryptographic
keys before the application protocol transmits or receives any data.
TLS is application protocol-independent. Higher-level protocols such as SIP can
layer on top of the TLS protocol transparently.
The IP phones use UDP as a standard for SIP transport, but they also support SIP
over TLS for added security.
To enable TLS for the phone:
Log in to the web administration interface.
Click Admin Login and advanced.
Click Ext <number>, then scroll to the
SIP Transport
Select TLS from the
Click Submit All Changes.
Configuring Security, Quality, and Network Features
SIP Settings
drop-down box.
Cisco SPA and Wireless IP Phone Administration Guide
Setting Security Features
section.