Cisco 8851 Administration Guide

Before you begin
Access the phone administration web page. See Access the Phone Web Page, on page 88.
Procedure
Step 1 Select Voice > Systems.
Step 2 In the Optional Network Configuration section, enter IPv4 or IPv6 address in the Primary NTP Server
and Secondary NTP Server .
Step 3 Click Submit All Changes.
Configure the RTP Parameters
Before you begin
Access the phone administration web page. See Access the Phone Web Page, on page 88.
Procedure
Step 1 Select Voice > SIP.
Step 2 In the RTP Parameters section, set the Real-Time Transport Protocol (RTP) parameter values as described
in RTP Parameters, on page 278.
Step 3 Click Submit All Changes.
Control SIP and RTP Behaviour in Dual Mode
You can control SIP and RTP parameters with SIP IP Preference and SDP IP Preference fields when phone
is in dual mode.
SIP IP Preference parameter defines which IP address phone tries first when it is in dual mode.
Table 12: SIP IP Preference and IP Mode
Failover SequenceAddress List from DNS, Priority, Result
P1 - First Priority Address
P2 - Second Priority Address
SIP IP
Preference
IP Mode
1.1.1.1 ->2009:1:1:1:1 ->
2.2.2.2 -> 2009:2:2:2:2
P1- 1.1.1.1, 2009:1:1:1::1
P2 - 2.2.2.2, 2009:2:2:2::2
Result: Phone will send the SIP messages to 1.1.1.1
first.
IPv4Dual
Mode
Cisco IP Phone 8800 Series Multiplatform Phones Administration Guide
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Cisco IP Phone Installation
Configure the RTP Parameters

Cisco 8851 Specifications

General

Brand	Cisco
Model	8851
Category	IP Phone
Language	English