Using Bluetooth

13 July 2004

My friend Ben gave me his old SonyEricsson T68i (which is one of the phones I've really wanted when it was new). It supports Bluetooth and AT&T Wireless provides my GPRS network, so this gives me something new with which to experiment.

I found a nicely-priced D-Link DBT-120 USB-BT dongle on eBay, and now I'm set. I thought it would be convenient just to be able to access the phone's modem functionality while it was still in my pocket, but it gets better than that -- I can put the phone on the other side of the house, where the GPRS signal is stronger and still access it from another room.

I recompiled my Linux 2.6.7 kernel with modules for: bluetooth, l2cap, rfcomm, hci_usb. I then installed Debian Unstable's latest bluez-utils package. I think the only bluetooth-specific configurations I needed to change was to add this section to the /etc/bluetooth/rfcomm.conf:

rfcomm0 {
    bind yes;
    device 00:0A:D9:13:0B:1B;
    channel 1;
    comment "T68i";
Restarting /etc/init.d/bluez-utils yielded a working /dev/rfcomm0 device which allows me to talk to the phone as a modem (just like ircomm0 in case of IRDA). I ran pppconfig and configured up a pretty standard modem-like PPP session using /dev/rfcomm0 as the device, bogus login and passwords, and relatively bogus default chat scripts. The important part is to dial to the right number: *99#.

My PPP connection kept dropping out after about 2 minutes, due to the lcp-echo requests not being answered. I had to disable lcp-echo requests with these 2 lines added to the /etc/ppp/peer/provider options file:

lcp-echo-failure 0
lcp-echo-interval 600
This disables failure, and additionally tells it to not ping so often (every 5 minutes now).

In my initial tests, I'm seeing about 4.5KiB/s, which isn't terrible for a completely mobile connection.

Filed Under: Linux Technology Computers