Good VOIP api, library, etc

Hello! I am new to all this VOIP thing. I am a developer and I have a few ideas with these tecnologies. However, i have some problem to find what i really want.
My idea is that I will have some text that i will transform into audio via a TTS. After that i have to call my client via sip (telmex or other) and play the prompt i have alredy made.
I was thinking to download some open sorce Soft-Phone and change the code according to my policies (for example if the line is busy or something else).
I believe that there must be something like this implemented, It doesn't have to be free or open source.
Does any body knows any api, library, etc?
I was thinking about HMP from Dialogic or Aculab, but i was wondering if there is something a bit higher-level than that?

Thanks in advance,
Hernan

Greetings Hernan and welcome to Voipuser

A reasonable starting point here ...

http://www.voip-info.org/wiki/view/Text ... h+from+DSC

If you can write an exact specification then its probably something a clever coder could write fairly fast or wouldn't be too hard to get Asterisk to do the job

http://asteriskvoip.blogspot.com/2005/0 ... xt-to.html

Thank you very much gray. I have been looking into asterisk pbx however i am not sure it is what i really need.
I think i didn't explain it well.I'll try to do it better .
I do not have any incomming call so i think a pbx wouldn't be that helpful. You can imagine that i will have a site where you can input some text and a telephone number.After that i have to make a voip phone call and use the tts to read the text. My trigger is not an incomming call. The trigger is submit button from a website.
To add more difficulty i wouldn't have lot's of lines. So i will have to apply any algorithm that is the person's line i am call is busy, then i will call another person and then i will retry the call to the first customer.

gray, with this scenario,
a)Do you think that asterisk would do the job?
b)Does this have any name in telephony so that i can find a product?
c)Would you consider using a soft-phone for this? I was thinking about using several in an application

Thank you very much gray, you answered really fast!
Hernan

Quote:

a)Do you think that asterisk would do the job? b)Does this have any name in telephony so that i can find a product? c)Would you consider using a soft-phone for this? I was thinking about using several in an application

a) Yes - but with additional programming
b) As far as I am aware, there is no product that does this 'off the shelf' which is why I gave you a link to a further long list of links. If you speak to each provider listed you may find one may well be working on varients of your requirements that may be adaptable and you will certainly learn a little more about what is already on the market.
c) No - Easier to start from scratch