I am very anxious about transferring my local phone number to Vonage
> because I am worried that users that can call me for free now, will no
> longer be able to. I live in the border line of two area codes, 225
> and 985, I can call my friends 985 number locally, no long distance
> charge, with my 225 number. However, since the number that vonage
> temporatily assigned to me is considered long distance to this town, I
> am scared that even though my current phone is local it might become a > distant number.
Before I answer, you should know I am not a big fan of VOIP. IMHO it is overhyped and there are many technical details (like 911 connectivity) to be worked out. IMHO (and personal experience) many of the sales people often give out incorrect information and do not have adequate resources to serve customers correctly. Thus, you may be promised something that doesn't come to be.
I also live in a border area as you describe and I have found outsiders -- like long distance carriers -- do not understand the arrangement. Long distance companies have billed me for local calls over the line and it was a fight to get the charges off.
I am afraid VOIP are spread too thin to understand these subtle arrangements and your concerns are completely valid. That is, you will end up with a number that is long distance for others to call you.