How to get n number of inbound call

In my project i am basically recording some messages. But it is not running well when i am giving 2 simultaneous calls. What to do in this condition. I am forwarding the incoming(from DID) call to a extensions and there i am doing the rest of the work. What will be the best solution if i want to make my project like it can handle n number of simultaneous inbound calls in it. Should i go for any extra feature or should i go for another provider(currently i am using nexvortex as our service provider). Please suggest me as this is the testing time of my project and i am stuck in it.