[root@localhost ~]# telnet localhost 8021
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Content-Type: auth/request
auth ClueCon
Content-Type: command/reply
Reply-Text: +OK accepted
event plain message
Content-Type: command/reply
Reply-Text: +OK event listener enabled plain
Here is gsmopen_dump
freeswitch@internal> gsmopen_dump gsm01
dumping interface 'gsm01'
interface_name = gsm01
interface_id = 1
active = 1
not_registered = 0
home_network_registered = 1
roaming_registered = 0
got_signal = 2
running = 1
imei = 352445045806115
imsi = 410040211858308
controldev_dead = 0
controldevice_name = /dev/ttyUSB3
no_sound = 0
playback_boost = 512.000000
capture_boost = 512.000000
dialplan = XML
context = default
destination = 5000
ib_calls = 0
ob_calls = 0
ib_failed_calls = 0
ob_failed_calls = 0
interface_state = 0
phone_callflow = 0
session_uuid_str =