Aastra SIP 53I Administrator's Manual page 157

Configuring Network and Session Initiation Protocol (SIP) Features
Network Settings
DSCP Range/VLAN Priority Mapping
DSCP bits in the ToS field of the IP header are set for RTP, RTCP, and SIP packets
using either the default values or the values configured via the "tos sip", "tos rtp",
and "tos rtcp" parameters.
When the VLAN global configuration parameter, "tagging enabled" is set to 1,
VLAN priority for IP packets is mapped to the DSCP value instead of a single
priority for all packets. An administrator can also configure VLAN priority for
non-IP packets using the "priority non-ip" parameter.
Since the default DSCP settings for SIP, RTP, and RTCP are 24, 32, and 32
respectively, this results in corresponding default VLAN priorities of 3 for SIP, 4
for RTP, and 4 for RTCP (based on the settings in the table
Priority"
You can change the default parameters by modifying just the DSCP values, just
the VLAN priority values, or by modifying all values.
The following table shows the DSCP range/VLAN priority mapping.
DSCP Range/VLAN Priority
41-001160-00, Release 2.1, Rev 04
on page 4-33).
DSCP
Range
0-7
8-15
16-23
24-31
32-39
40-47
48-55
56-63
VLAN Priority
0
1
2
3
4
5
6
7
"DSCP Range/VLAN
4-33