Developer to help integrate IP Telephony/CRM/e-commerce site/payment gateway

We're looking for a web developer to help us build a paid telephone help center system. Customers buy credit on our website and dial a local number with their PIN to connect to our agents and receive help. The technical infrastructure must integrate: -- IP telephony system with billing (e.g. something like this: [login to view URL]) -- CRM -- e-commerce website in Chinese and English (will likely have to be an open source cart as PayDollar only integrates with open source carts) -- payment gateway that will accept Alipay, credit cards and Paypal (probably PayDollar as it is the only one we've found that allows Alipay) We'll need your help to -- design the system (starting with choosing the software) -- help us to integrate/configure the pieces so that the data flows through correctly -- maintenance / tweaks once it's up and running We are currently speaking to various telephony vendors to find a suitable partner to provide the PBX. You will work in tandem with their technical staff to make sure that data flows through the entire system. We may consider taking someone on as a permanent part of our team. In your proposal, please share your preliminary thoughts on how this system could work, any challenges you foresee, and what experience you bring. I've listed our budget as >$5,000 but we really don't have a set budget in mind. We are looking for high-quality work, but we are a start-up and our funds are not unlimited.