ringtone prob with t230

hi
i've managed to hook my t230 up to my computer and downloaded some ringtones from other sources, they are midi sequence files but every time i try and put one on the phone it always says that theres not enough space left on the phone, I dont understand this cos the tune that i tried to put on was only 1kb and there was 662kb left on the phone to start with but it still filled it.
Could someone tell me if i'm trying to put the wrong type of files (i.e are they midi files or mmf files etc)

sedge :cry: :cry: :cry: :cry: :cry: