Playing a recording through an iPhone?

[chrisjchrisj]

When I have to do a lot of calling for work, via my iphone, and I've reached the voicemail of the prospective client (who opted-in for information), and I have to repeat why I'm calling over and over throughout the day, when leaving a voicemail message, it would be helpful to instead to play a recording of what I have to say, because after several calls, I start to not sound as professional.

So, a recording of me would help my job, rather than me saying the same thing over and over again. I know that there are external microphones available for iphones, so I thought their may be a solution for my situation, maybe hooking up a digital voice recorder, or something/somehow?.
Any ideas how I could play a recording through my iphone, when needed, will be appreciated.