Recording voices for Opening sequence

For our film, we decided to record the actors voices in order for our audience to perceive the voices as part of a telephone answering machine. We have done this by recording with a camera and placing the audio as a voiceover in the opening title.  This is so that we are able to show to our audience that somebody (the person revealed at the end of the opening sequence) is missing but still creates an element of mystery as we do not know why or how they came to be missing. This is done so that  enough knowledge is enabled to be gained by the audience, but not too much so that the audience is still intrigued by the opening title.