vTiger 5.1 already has an integration set with Vicidial, but it's old and vTiger itself is not that cool from a programmer's standpoint. Don't flame me, I've read the code and it's not clean or professional. It does get the job done, though, after a fashion. LOL
But if you are not prepared to deal with a very old version of vTiger, you could try a later version and look at upgrading the built-in integration. Or you could try SugarCRM which has superior coding ... but is missing group level security (on purpose!).
In any case, I'd use the latest version of any CRM when and where possible. But that's me.