"Is the phone in the bedroom?"
Translation:Aia ke kelepona i ka lumi moe?
The words ka and ke both mean the in English. You use the word ke before words starting with the letters k, e, a, o. Please keep in mind that words starting with the glottal stop / ‘okina still count as starting not with a vowel but that consonant - ke oho but ka 'ohe, for example.
There are exceptions to this, including ke ‘ala, ke po'o, ke pākaukau, etc.