Start VOIP business

Hello Everybody,

I want to start voip business, What I planning to do is this:

1. I wants to establish a reliable gateway with billing system at my location.

2. My customer using ip phone (dailup) or small 1 port Gateway will call through my gateway to pstn line.

So please tell me what is the reliable Gateway with billing and what is the ip phone (dialup).

Does any one help me.

I appreciate your input

Thanks in advance.