VoIP Telephony Solution (A2billing Configuration)

Hello, I want to create a voip system for a small community. I basically want to create a voip platform that will be equivalent to a standard residential telephony service however with only two servers (or 3 max). The first server will play the role of a sip proxy, load balancer, SBC and media proxy. The other two will be telephony servers (i.e asterisk) that will handle the calls. The system must be scalable so when the capacity is reached on the fist two servers, a third can be added. You are required to utilise: -A good SIP proxy to take care NAT bursting and media RTP issues (OpenSips?Kamailio?Freeswitch? You need to select which one and justify the reason behind.) -A2billing for the billing part. Here you are required to enable the following common functions: 1)Voicemail: Users should be able to see (and listen) to their voicemails via their A2Billing Customer interface. 2)Follow me number. Users should be able to select a follow-me number that will be billed according to their active tariff. (If the forward is to a voip (SIP) number then there's no charge. 3)Fax2email. Each user should be able to receive a fax in his email. (Hylafax is a possible suggestion). User should be able to configure this via the A2Billing interface. ------------ I will provide you with access to the two servers so you can perform the installation and testing. You will be required to demonstrate to me the load balancing abilities of the setup. For example, when Telephony Server 1 is full of calls then the proxy sends the calls to the second Telephony server (the 2nd telephony server will also be provided for this test). The tests should be performed with appropriate testing software provided by you. This is a telephony project for a small community and it should not be regarded as a large project. Your quotation must take this into consideration. If (and only if) the project turns out successful financially, then further investment will be done and hence you will be doing the further development! If you have done such a thing before then you'll know that most of your time will be spent on doing the voicemail/follow-me/Fax2Email integration and not in the general setup. If you have any questions please let me know. Please do not bid if you have never done this before. You will be wasting both my as well as your time and there is no need for this! Please also note that the project is advertised elsewhere as well. Thank you. Tags: Integration, LAMP, Asterisk, A2Billing, Fax2Email, Follow-me, OpenSips / Kamailio, RTP, SBC, SIP, Telephony, Voicemail, Voip