HTC released an official update on their European website for the HTC TyTN II, addressed especially for the Portuguese version of the device.
According to the description, “this update for your HTC TyTN II gives you more flexibility in creating SMS messages, now free of the length limitations from before”.
Not quite sure what this does since SMS message lenght is 160 characters by design. My best guess is that when you reach the end of the 160 characters, the system will jump to creating a second SMS message continuing the first one. Drop us a comment if you know more about it.