Deborah, Indigo's post reminds me that there is another way to do voice banking while you are waiting to see if Model Talker can work for you. MT is unusual in that it has you record all these short nonsense phrases and then it creates a synthetic voice that imitates yours. I should warn you that it took me almost 2 months to do the whole suite of recordings. Now I only did about 10-20 minutes a day but my voice got tired after that much talking. Also I am a perfectionist and would record over any phrase where my voice cracked or otherwise did not sound my best. Despite all this I don't think the voice quality is all that good in the end result. It sounds like the love child of me and Steven Hawking. Plus the voice synthesizer is somewhat primitive and produces electronic-sounding tones for certain vowels. So there is a tradeoff, the voice sounds something like me but the quality is more electronic than the good commercial voices that are available today.
The other way to do voice banking is simply to record phrases in your own voice that you will be able to play back later. Things like "Good morning", "How are you?" "Please get me some sugar", etc. This is really what most people mean by voice banking. The Model Talker stuff is a little more exotic.
One program I have used is called etriloquist,
E-triloquist . It can both say phrases using a computer voice, and also lets you record your own. You will have to study the manual to figure out how to record your own, it is not too obvious, and if you need help just ask here. etriloquist can also be set up later to use the voice from Model Talker if you go that route.