Dear Matt, A small group of ser users have started to write a Getting Started document that will address many of your questions. A date for a first draft is not yet set, but the draft will be posted to this list.
To your questions:
I'm a new user of SER. Just some questions about how I could deploy SER+SERWEB+SEMS, possibly on separate hosts, as I plan to have more than one SER proxy server with a centralized web server and media/voice mail server (1) Basically what features will I be missing if I decide to omit the fifo functions (if possible) in serweb? ( aliases, add new contact SIP address and who are online would be three features, right?)
Standard ser does not have network-based FIFO functionality. Various initiatives have worked on this issue. Meanwhile, my advice is: Do not start with this complexity. Use FIFO (only thing serweb supports today), install serweb on the same server as ser, get it up and running and start the learning curve.
(2) I saw in one of the threads that there is a fifo_server.php file available for fifo-Internet relay, but not quite sure how to use it. Could someone give me some pointers?
cvs 0.9.0 in the utils directory.
(3) Somewhere in the mailing list I saw the "fifo_db_url" global declaration, is it a feature only available in version 0.9.0? And is there a serweb version that will work with ser 0.9.0?
Yes. And no, I believe serweb is not yet fully functional with 0.9.0.
(4) I have not tried SEMS yet, but since it also communicates with SER via fifo, I would assume it has to be in the same host as SER, right? Are there any existing modules/plugins that will allow SER and SEMS on different hosts? If not, would it be more scalable if I build an Asterisk box to handle voice mails?
No, sems uses a full ser instance as its front-end. See examples supplied.
There are different opinions as to whether sems is mature enough to handle voicemail. It depends on your needs. In the Getting Started doc we will use Asterisk.
(5) If I have multiple SER proxy servers on different hosts, how could UA Alpha registered with SER proxy A be able to call UA beta which registered with SER proxy B? What setup/configuration would I need?
There are no short-cuts to accomplishing what you want. You need to fully understand how proxying and other things work. Start out with a tutorial, read the admin manual, and go through the serusers list on mail.iptel.org. http://www.iptel.org/ser/sipintro.html http://www.iptel.org/sip/ http://www.iptel.org/ser/admin.html
g-)