[Serusers] VoIP Solution !!!

Hi guys, I know that it might not be the right question to the list but, i'm testing various voip solutions, and what I need is a solution that gives me the possibility to make sip calls, associated also to a PSTN, with also authentication properties like, the server auth at another server and so on. I need it integrated with a database, such as mysql, and also a billing system. Is mainly important that all or nearly all the configuration could be done by an Web Interface to make things easier, at least my clients provisioning. I've looked for this type of solution, and found various softs that does that, but i'm not sure which one is the best for it ... What I've found best for me is asterisk, ser, b2bua (sip softs), with mysql as the database, and cdrtool, voxbox as a Billing System and Web Interface. I'd like to know what are your experiences, and what kind of system and softs do you use. If you have a similar solution to what I want, please let me know, i'm already under higher sector's pressure, and it's starting to annoy me :o) Any help will be welcome !!! -- Felipe Martins Linux System Administrator Tep Solution Provider Mundivox Communications Rua Lauro Muller, 116/Sala 505 RJ - Brasil - 22290-906 Tel.: 55 21 3820-8839 Fax.: 55 21 3820-8844