Is "ett mobilnummer" a thing?
Yes, that's perfectly fine if referring to a cellphone number. :)
That's what I expected :)
en telefon, but ett telefonnummer. Correct?
i've found that in compound words, the gender matches the last word usually
Yes, that's the rule.
Can "phone number" work here as well?
In english and dutch most of the time only 'number' is used. In swedish as well?
"Har du mitt nummer?" is a common way of expressing it.
Am I wrong or TTS pronounces the question with too flat intonation? Shouldn't the voice be higher in the end?
Perhaps the TTS should raise the tone to mark the question, but I guess that's hard for a robot to do correctly.