Wednesday August 10, 2005

Treo 650 DUN

I have been having troubles with using Bluetooth DUN between my Treo 650 and my Apple Powerbook 12" running MacOS X. For a good description of how to configure it check out this thread on TreoCentral or vocaro's excellent summary. It mostly worked just fine, but every 5-60 minutes the laptop would get an RFCOMM error and drop the connection. Trying to immediately re-connect would fail with the same error. But if I turned off Bluetooth on the Treo and then immediately turned it back on again it would come back. Very annoying, but it mostly worked.

On my last trip I started to get very annoyed. Searching places like TreoCentral, would find that most people used DUN without any problems (assuming their carrier's version supported it), but a few would have problems similar to mine, but with no real fix available. So I started googling and just happened to stumble into PhilMUG's website and saw this passing configuration notes about the System Preference->Network->Location->Bluetooth->PPP without explanation:

    Click PPP Options.
    - set all boxes as unchecked

and

    Select Bluetooth Modem
    - Select Treo 650 Globe GPRS as the modem. 
    - leave both Enable error connection and compression in modem and
       Wait for dial tone before dialing options unchecked.

I looked in my laptop's Network Preferences and I did have some of those boxes checked. I cleared them and so far have spend 4-6 hours connected using DUN without any RFCOMM errors. I have not gone through and systematically tried each of them separately to see which are the culprits, but I suspect it may be the "Enable error correction..." and/or "Use TCP header compression." My weak theory is that the Bluetooth link has bit errors that the correction or compression cannot deal with resulting in an error. Without checks the junk goes through but is dropped by the TCP/IP stack.

So far my DUN usage has been from the mundane hotel usage to gain 100+kbps over a dialup ISP (and the infamous 60+ minute charges), to web surfing in an RV parked in a field outside Sears Point Raceway! Not as fast as a WiFi hotspot, but it sure works in a lot more places. Now if wireless vendors could come up with cheaper data rates and better GPRS/EDGE coverage I would be really happy! ( Aug 10 2005, 08:57:12 PM CDT ) Permalink Comments [2]