[asterisk-biz] Comments Required on asterisk2billing 120 concurrent calls limits!!

Hi! I would like to implement a2billing for calling card business. I would like to know the concurrent call limitation by asterisk2billing that is 120? I believe that a single asterisk box can handle 8 E1 TDM Calls or 300 to 500 SIP calls easily on a good Xeon server with 2 to 4 gb RAM with g729 codec. Please comments on following statement given on at http://www.asterisk2billing.org/cgi-bin/trac.cgi See this line The platform can be fitted with a TDM cards to interconnect with the PSTN, and can support in excess of 120 concurrent calls given the right hardware. If more capacity is required, then more Asterisk servers can be added as necessary. Also if some one refer to good documentation about how to add multiple asterisk server with a single A2billing engine. Or a case study of deploying a2billing for calling card business with larger call volume. Your Comments are welcome. Thanks With Regards Muhammad Zulqarnain