Encrypt Signaling With Sip Over Tls; Configure Voice Codecs - Cisco 8831 Administration Manual

Chapter 4 Configure Security, Quality, and Network Features
To configure SIP INVITE challenge, navigate to Admin Login > advanced > Voice > Extension. Under
SIP Settings in the Auth INVITE field, choose Yes.

Encrypt Signaling with SIP Over TLS

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:
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The IP conference phone uses UDP as a standard for SIP transport, but they also support SIP over TLS
for added security.
To enable TLS for the phone, navigate to Admin Login > advanced > Voice > Extension. Under SIP
Settings, select TLS from the SIP Transport list.

Configure Voice Codecs

A codec resource is considered allocated if it has been included in the SDP codec list of an active call,
even though it eventually might not be chosen for the connection. If the G.729a codec is enabled and
included in the codec list, that resource is tied up until the end of the call whether or not the call actually
uses G.729a. If the G729a resource is already allocated (and since only one G.729a resource is allowed
per IP phone), no other low-bit-rate codec can be allocated for subsequent calls. The only choices are
G711a and G711u.
Negotiation of the optimal voice codec sometimes depends on the ability of the conference phone to
match a codec name with the far-end device or gateway codec name. The phone allows the network
administrator to individually name the various codecs that are supported such that the correct codec
successfully negotiates with the far-end equipment.
Note that the conference phone supports voice codec priority. You can select up to three preferred
codecs. The administrator can select the low-bit-rate codec used for each line. G.711a and G.711u are
always enabled.
TLS Record Protocol--layered on 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--authenticates the server and client, and negotiates the encryption
algorithm and cryptographic keys before the application protocol transmits or receives data.
Cisco Unified IP Conference Phone 8831 for Third-Party Call Control Administration Guide
Configure Voice Codecs
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