"We call them and they change it."
Translation:Vi ringer til dem og de ændrer det.
This, because "kalder" means more in the sense of: "we have named them this, and thus we refer to them as this"
It isn't. Whether "den" or "det" should be used would depend on the grammatical gender of whatever the pronoun is referring to. For instance, you may have an appointment ("en aftale") with someone, and you might want to cell them to have it changed. In that case, it would be "den".
There is no suggestion of the phone ringing at all in the sentence, so why should it be in the translation?
Apparently what I have figured out my way is:
Kalder is specifically for 'when you call for someone', it could be help/support/or anything, like for example 'Drengen kalder på pigen' would be translated as 'The boy calls for the girl'.
'Drengen ringer til pigen' is more like 'The boy calls the girl'. This one is more used for phone context.
I hope it's understandable. :)
Vi ringer til dem og de skifter det. = Incorrect because apparently we're not supposed to know the verb "at skifte" yet. :/