in Planet Debian selfnote ~ read.

[selfnote] Find the DUN Channel of your bluetooth device

In the last days, I replaced my Nokia E90 with a Nokia N97 mini. As I'm using my mobile from time to time to hook up to the internet when traveling, I thought I just need to replace the MAC in my /etc/bluetooth/rfcomm.conf and that's it. As always ... Murphy striked back. After debugging for hours I realized the DUN channel seems depending on the model.

You can discover your DUN channel something like:

# hcitool scan
Scanning ...
	3C:F7:2A:1A:4D:2A	Cycophone
# sdptool browse 3C:F7:2A:1A:4D:2A | \
 grep -9 "Service Name: Dial-Up Networking" | \
 tail -10 | grep Channel
    Channel: 22

So your /etc/bluetooth/rfcomm.conf should now look like:

[...]
rfcomm0 {
bind yes;
device 3C:F7:2A:1A:4D:2A;
channel 22;
comment "Cycophone";
}
[...]