[Serusers] Asking for advice

Hi,

I'm new in IP Telephony world and I began from the beginning using SER ...

I have found it very nice, simple to configure/use ... Althoug I've had some problems in redhat9.

Ok, some days ago I was talking to a friend of mine who was investigating on VoIP and tall me about VOCAL from Vovida.org and Asterisk ...

I have read something about Asterisk in this mailing list but I hadn't know of VOCAL ...

Could any one tell me about the open source SIP platforms in the todays world ?

Their differences ... Etc ...

And also the Oparating Systems usually used for this ... (I work with RedHat Linux 9)

I'm working for a really good solution for my University VoIP platform ...

Thanks,

Robert.