I hesitated to post this as I'm sure it must have been done before - can't find it though. Also can't find any 'cellphone' or 'mobile' categories ...
(Sorry - been away rather a long time!)
How many times do you start texting away only to look and see that you were in wrong T9 mode and have a meaningless array of letters, so have to go back and do it again?
Phone should have a select and fix option! (PS - maybe some do, but I don't think mine does!) i.e. select all the text that went in wrong and select the mode that you wanted it in instead ('123', 'Abc', '_Abc', etc)
Could even have secondary use as a secret code generator (various uses - perhaps vs. 'leet'ers?).
Create your text message normally, select it & convert to '123' mode to get all the individual keypresses. Paste that wherever you want it to look meaningless. The recipient sticks the digits into their phone, selects & converts to '_Abc' mode and bob's their cousin's male parent.-- kindachewy, Jun 24 2009 Oops - just realised a major problem with this is that the final stream of digits doesn't contain enough information (by itself) to determine how they were entered. e.g. is '9999' a single z, or a w followed by a y?-- kindachewy, Jun 25 2009 Now you are right...-- 4whom, Jun 25 2009 [+] Made me think of an 'I spell like an idiot' button which when pressed would allow you to scroll through the list of possible corrections for the word. Why do cellphones not underline incorrectly spelt words? This idea could be useful for cellphones too. Will add the idea and see what people say.-- danman, Jul 06 2009 My guess, they'll break down and weep for their lost splnk inncnc. Nobody's supposed to care about this stuff anymore. The other day, I didn't.
I can think of three ways to solve the disambiguation problem, [kindachewy]. The methods can be combined.
(a) Heuristics. Store which character combinations are actually likely, and pick the most likely ones.
(b) User input. Starting with a pretty good interpretation, have the user easily cycle through the less likely options.
(c) Just store the frickin' timing data! Just because *you*'re limited in input bandwidth, your phone doesn't have to play stupid. The phone could easily remember whether you typed aaa,a or aa,aa, and display the correct result for the rhythm you used when you entered it.-- jutta, Jul 06 2009 Good suggestions - I think it'll be a + b
(c could work on the phone, but not for the 'secret code' application!)-- kindachewy, Jul 06 2009 I had an idea about T9 texting that I left in an anno somewhere.. I should have put it here. :(-- daseva, Jul 06 2009 random, halfbakery