Feel your pain and everyone here has tried to help me as well. I have spent hours trying to find the very same answer and have tried loading the cab posted on my post a few days ago, you could try it I suppose it did not work for me. I have given up for now,, nothings seems to work except some saying to cook your rom which is risky and could void your warranty,,, and even then some say that works as the cab was suppose to work so it's user beware and you just have to keep reading here or give up. I hear that if you cook your rom that you could remove it before taking your phone to your provider if you needed to, not sure of that need to search some more here.
I keep looking back here for hopefully someone that will have a All-tell PC-6800 and have been able to make there's work. I would look as I am for someone that is using the same phone and rom, radio version that has had success, I don't know what else to say. Plus searching through here you learn a lot more about themes, rom, lots of cool mod's.
The cab is on my post by Keir333 he says he has the same phone as I do so I am not sure that would be the one you would want to use. I thought I would look for someone with the same phone and he has the same as mine, same rom and radio version and the cab still did not work on my, go figure.
I would also post info like your phone carrier, type of phone, rom and radio version.
I would not take it personal what Jethro posted even he post the same thing multipule times like Opera, Iphone, mogul, etc we all do it in search of answer's.
You can do a search on a person's ID for there post for laughs plus helps when you find someone that really know's there modding....
Good luck there are alot of good info and people here.
Cheers,
Azbobs