Cisco IP Phone 6851

Transport Layer Security
Transport Layer Security (TLS) is a standard protocol for securing and authenticating communications over
the Internet. SIP over TLS encrypts the SIP messages between the service provider SIP proxy and the end
user. SIP over TLS encrypts only the signaling messages, not the media.
TLS has two layers:
• TLS Record Protocol—Layered on a reliable transport protocol, such as SIP or TCH, this layer ensures
that the connection is private through use of symmetric data encryption and it ensures that the connection
is reliable.
• TLS Handshake Protocol—Authenticates the server and client, and negotiates the encryption algorithm
and cryptographic keys before the application protocol transmits or receives data.
The Cisco IP Phone uses UDP as the standard for SIP transport, but the phone also supports SIP over TLS
for added security.
Configure SIP Over TLS Signaling Encryption
Procedure
Step 1
To enable TLS for the phone, in the phone web user interface, navigate to Admin Login > advanced > Voice
> Ext(n), where n is an extension number.
Step 2
In the SIP Settings section, select TLS from the SIP Transport drop-down list box.
Step 3
Click Submit All Changes.
Documentation, Support, and Security Guidelines
For information on obtaining documentation, obtaining support, providing documentation feedback, reviewing
security guidelines, and also recommended aliases and general Cisco documents, see the monthly What’s New
in Cisco Product Documentation, which also lists all new and revised Cisco technical documentation, at:
http://www.cisco.com/c/en/us/td/docs/general/whatsnew/whatsnew.html
Subscribe to the What’s New in Cisco Product Documentation as a Really Simple Syndication (RSS) feed
and set content to be delivered directly to your desktop using a reader application. The RSS feeds are a free
service and Cisco currently supports RSS Version 2.0.
Cisco Product Security Overview
This product contains cryptographic features and is subject to U.S. and local country laws that govern import,
export, transfer, and use. Delivery of Cisco cryptographic products does not imply third-party authority to
import, export, distribute, or use encryption. Importers, exporters, distributors, and users are responsible for
compliance with U.S. and local country laws. By using this product, you agree to comply with applicable
laws and regulations. If you are unable to comply with U.S. and local laws, return this product immediately.
Cisco IP Phone 6800 Series Multiplatform Phones Administration Guide
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Documentation, Support, and Security Guidelines