[Serusers] why combine ser with asterisk

[Nhadie]

Hi All,

What's the advantage of combining ser with asterisk? I always see 
comments like using ser with asterisk is a very good solution etc. etc.
the thing i liked with ser is that it does not do codec translation, 
which saves me cpu usage and also bandwidth. if i combine it with 
asterisk, would it not use codec translation?

i also read that there is also a problem when ser and asterisk is run on 
the same machine, why is it so?
if use prepaid billing solution for asterisk like astcc, would i then be 
able to provide prepaid service?

soryy for asking too much, i'd just like to really understand it. Thank 
You in advanced.

Regards,
Nhadie