For phones, i would recommend twelve key keyboard, it might not be fast, but it helps you use only hiragana or katakana, not a native btw.
For laptops romaji is the only option, even i faced issues with it, in my version, i have to choose between a many options and most of the time, it doesn't have what i need, i am a beginner, so I just need 五時,六十時etc,and it doesn't provide them. also it doesn't provide the ん letter most of the times.
Hope it helps