Getting online with GPRS in India

In order to get online using GPRS you would need:

1. A device capable of handling GPRS; usually a cell phone or a GPRS modem. I've used a Nokia 3110c with some success. This particular cellphone model offers a USB port using which it may be connected to a host computer with a compatible USB cable.
2. A subscription to GPRS service. Contact your cell service provider on the way to enable this on your cell phone. The examples below describe the configuration needed for using AirTel's GPRS service.
3. The appropriate configuration for your OS. This post describes how to use GPRS using FreeBSD and NetBSD.

FreeBSD Configuration

1. Ensure that the relevant drivers are present in the kernel. The Nokia 3110c is supported by the stock umodem(4) driver. Use kldload(8) to load this into your kernel if it is not already present:

   # kldload umodem
   

2. On connecting the cellphone to the computer, you should see a message similar to the following on the console (or in /var/log/messages):

   ... kernel: ucom0: Nokia Nokia 3110c, rev x.yy/a.bb, addr 2, iclass 2/2
   ... kernel: ucom0: data interface 2, has CM over data, has break
   ... kernel: ucom0: status change notification available
   

   If all goes well, a new device entry such as /dev/cuaU0 should be present under /dev.
3. Add the following to /etc/ppp/ppp.conf (note the leading whitespace on most lines):

   airtel:
    set device /dev/cuaU0
    enable dns
    set phone "*99***1#"
    set authname "airtel"
    set authkey "airtel"
    set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 5 \
     \"\" AT OK-AT-OK ATQ0V1E1S0=0&C1&D2+FCLASS=0 OK \
     AT+CGDCONT=1,\\\"IP\\\",\\\"airtelgprs.com\\\" OK \\dATDT\\T \
     TIMEOUT 40 CONNECT"
     add default HISADDR
     set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.0 0.0.0.0
   

   For the curious, the ppp(8) manual page fully describes the syntax and semantics of the configuration commands above.

   Note that the contents of the authname and authkey configuration items do not seem to matter. You could put the name of your pet dog there if you wish.

4. Invoke the ppp(8) daemon in the usual way:

   % ppp airtel
   ppp> dial
   ... the prompt changes as PPP setup progresses
   PPP>
   

   And you should be done.

NetBSD Configuration

In NetBSD as in FreeBSD, this particular cellphone model is supported by the umodem(4) driver. Once recognized, the modem will be accessible using a path name such as /dev/ttyU0.

The following recipe uses the pppd(8) daemon. This recipe requires the NetBSD kernel to have been compiled with in-kernel PPP support.

1. Create a file /etc/ppp/peers/airtel with the following contents:

   ttyU0 115200
   connect '/usr/sbin/chat -v -f /etc/ppp/chat-airtel -T "*99***1#"'
   defaultroute
   usepeerdns
   ipcp-accept-local
   ipcp-accept-remote
   user "airtel"
   password "airtel"
   

2. Create a file /etc/ppp/chat-airtel with the following contents:

   ABORT "BUSY"
   ABORT "NO CARRIER"
   ABORT "ERROR"
   ABORT "NO ANSWER"
   "" "AT"
   OK "ATQ0V1E1S0=0&C1&D2+FCLASS=0"
   OK AT+CGDCONT=1,\"IP\",\"airtelgprs.com\"
   OK \dATDT\T
   TIMEOUT 40
   CONNECT
   

3. Start ppp using:

   # pppd call airtel
   

   Monitor /var/log/messages for error messages.

4. Once the connection is setup, IP addresses for the ISP's DNS servers would be placed in /etc/ppp/resolv.conf. Add these to /etc/resolv.conf if needed.

Connection performance

In my experience, connection speeds vary widely from a few bytes/second to a peak of a few KB/sec. Connection latencies also tend to be variable, ranging from a few hundred milliseconds upwards. There are frequent long pauses, a minute or more in duration, during which no traffic flows (though the connection remains up).

Thus GPRS based connectivity is best used for batch tasks such as downloading and sending email.

Slowly getting back online

One of the prices paid when I moved out to rural India last year was loss of connectivity.

For many months, there was no reliable way for people to call and reach me. As for internet access, I used to go to the nearby town (20km away) to an internet parlour from where I would access the 'Net---if there was power in the town to do so. Keeping my FreeBSD CVSup repository in sync used to be a interesting challenge, as was keeping up the communication flow with my two GSoC'07 mentees.

Connectivity options began to improve about a month ago: AirTel's cell service started up in the area so I could get online using GPRS. And then, last week, BSNL started offering DSL service in this area.

In the past year I explored various options for getting online as a FreeBSD user; I will describe these here by and by. Stay tuned!