Cisco 7821 Administration Guide

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
2009:1:1:1:1 ->
1.1.1.1 -> 2009:2:2:2:2 ->
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
2009:1:1:1::1 first.
IPv6Dual
Mode
2009:1:1:1:1 -> 2.2.2.2 ->
2009:2:2:2:2
P1- 2009:1:1:1::1
P2 - 2.2.2.2, 2009:2:2:2::2
Result: Phone will send the SIP messages to
2009:1:1:1::1 first.
IPv4Dual
Mode
2009:1:1:1:1 -> 2009:2:2:2:2
->2.2.2.2
P1- 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.
IPv6Dual
Mode
1.1.1.1 -> 2.2.2.2P1 - 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.
IPv4
or
IPv6
IPv4
Only
2009:1:1:1:1 ->
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
2009:1:1:1::1 first.
IPv4
or
IPv6
IPv6
Only
SDP IP Preference - ALTC helps peers in dual-mode negotiate RTP address family.
Cisco IP Phone 7800 Series Multiplatform Phones Administration Guide
57
Cisco IP Phone Installation
Control SIP and RTP Behaviour in Dual Mode

Cisco 7821 Specifications

General

Brand	Cisco
Model	7821
Category	IP Phone
Language	English