Draytek Telnet Command 1.11 - Manual (Page 123)

Telnet Command Reference Guide V1.1 117
2.23.5.4 voip sip misc (for 2800 series)
This command allows users to set miscellaneous settings for the device.
voip sip misc [- | ... ]
Syntax Description
The available commands with parameters are listed below.
-c Enable compact header (0: disable, 1: enable)
-i Enable CODEC change w/o Re-INVITE (0: disable, 1: enable)
-r ISDN On/Off Net retry counter (3 ~ 255, default is 3)
-v View current settings
[…] It means that you can type in several commands in one line.
Example
> voip sip misc -v
sip misc. settings:
Use compact header: no
Alter codec no INV: no
Auth. retry times : 3