THOMSON ST2030 SIP Administrator's Manual page 180

ST2030s VoIP Business Phone
C) Through Telnet:
For this purpose, two new parameters have been created, described as
follow:
sys set PBXconfiguration (0: default setting 1: phone behind a PBX)
sys set PBXprefix (0 to 9, * or #)
To configure, open a command line console, and telnet the phone:
ST2030s SIP Administrator Guide v3.0 Page 172 of 308