Ring length is set by your carrier, not by the device. If the device's volume adjustment isn't cutting it then edit the audio file on your computer and adjust the volume level in the file itself. You can't "crank the iPhone to 11".
iJailbreak had a tutorial for manually editing files using iFile. It was written for ios4. I followed the steps and my volume was absolutely louder than stock. In fact, when you edited the files, you could change the values so dramatically that the volume would be too loud. It would get very distorted and would sound terrible. Plus it would eat battery life. But the tutorial does work. Unfortunately I'm on iOS5 now and even though the site says the tutorial will work on iOS5, it doesn't work. Plus some of the files are located in different folder locations. I read on other blogs where people located the files and said it works for them, but I tried that as well and didnt get the same results as on ios4. I can post a link to iJailbreak of anyone wants to mess around with it. If anyone successfully gets it to work I'd love to hear from you!
I downloaded the newest Volume Boost for iOS5.x.x in one of cydia's default repositories, but I dont think it works as advertised. It says the volume is increased by 30%. I can't notice a difference. Man I wish that old tutorial still worked!
EDIT: Very strange. I just went into cydia and removed the Volume Boost by Fl4kz to see if I could notice a difference in volume. After it was done uninstalling and I returned to cydia, cydia told me the package could not be found. I then searched for it but it is no longer in the default repo. I wonder why its gone? Maybe it was confirmed not to work? Very strange...