How many sip-client does one asterisk server can support?

As I 've seen asterisk is not a complete sip server but how many sip client does asterisk support? I don t want to use asterisk with SER so how can I gurantee asterisk can support my client. And why this?
Thanks a lot…

I think its not a question of how many SIP clients but rather how many number of concurent calls can it handle. Though we realy havnt tried it but I read it somewhere, some kind of a rule of the thumb. It says that a Pentium 4 2.8GHz processor with 512MB memory and 80GB HDD can handle 200CPS or calls-per-second. But to be on the safe side and as practiced by telcos, you only utilize 50% of your resources. So safe to say a server can handle 100CPS for reliability.