How do I enable Umlauts on "Phone Keypad"-style keyboard?

First of all, I know long pressing on a char like 'a' gives me choices e.g. 'aä..' so the special char (umlaut) 'ä' can be selected. But this works *only for me for the "international"-style keyboard* (aka QWERTZ keypad). When switching to "Phone Keypad"-style keyboard (aka multitap/T9 keypad or 4x3 keypad), I will have no umlauts, though correct localization (set to "German"). Do you have any tips to make it work? I also observed the same behavior for the "Compact"-style keyboard. **Phone:** * HTC Desire S * has Android 2.3.3 stock firmware * No additional keyboard apps, as I recently bought the phone (5 days) * Not using Swype (I know that this has pretty nice umlauts handling due to the dictionary)