[support] Help with payment solution development(Call back url)

I am developing(rather adapting uc_echecknet) for a local payment solution. The payment solution provider posts the results back to my shopping cart to a callback url. I am able to post data to the provider...but I am not sure which url to give the provider. Is there a stardard one or do i need to create one with the module? Any direction on how to do this? Thanks