Instant Internet
25.06.2008 17:29
Today I had the opportunity to play with an USB HSDPA modem. This is the latest generation of the packet data connection through a cellular network which can in theory get you a 7.2 MB/s downlink. You get it in a soup can in combination with some subscription plans at Mobitel.
The modem itself obviously has several names, depending on who you trust:
- The advertisement says it's "GlobeSurfer iCON 7.2",
- the front side of the modem says "Option",
- the back side says "Qualcomm 3G CDMA model GI0205"
- and finally lsusb says it's "Globetrotter HSDPA Modem".
It certainly gives you the warm feeling that various marketing departments are working together to reduce the confusion here. Just for the record, USB ID is 0af0:6911.
Anyway, the thing works without problems on Linux. It is used as a standard serial modem with a PPP connection, except that you need to give it some special AT commands first.
When I plugged the modem in I got three USB serial devices: /dev/ttyS0, ttyS1 and ttyS2. First two didn't respond to any AT commands, while ttyS2 responded with the usual OKs. I didn't need to do any extra steps to switch the hardware from the simulated CD mode to modem mode as some people reported.
The actual configs I used are here. I don't know why, but sometimes two attempts are necessary to get a connection.
# pppd configuration (e.g. /etc/ppp/peers/qualcomm) # Change if using with some other mobile provider user "mobitel" connect "/usr/sbin/chat -v -f /etc/chatscripts/qualcomm /dev/ttyUSB2 115200 noipdefault usepeerdns defaultroute noauth crtscts passive modem idle 7200 # No support for compression noccp novj
# chat script (e.g. /etc/chatscripts/qualcomm) ABORT BUSY ABORT VOICE ABORT "NO CARRIER" ABORT "NO DIALTONE" ABORT "NO DIAL TONE" TIMEOUT 5 "" ATZ OK ATE1 OK AT+CPIN? # insert your PIN here READY\r\n\r\nOK-AT+CPIN=your_pin_here-OK AT OK AT+CGDCONT=1,"IP","internet","0.0.0.0",0,0 OK AT+CGDATA="PPP",1 CONNECT ""
You also need to enter a proper username and password into chap-secrets file (PAP authentication isn't supported). For Mobitel this pair works:
# Secrets for authentication using CHAP # client server secret IP addresses mobitel * internet *
