Bypassing payment gateway

Hello!

I'm trying here to setup WHMCS for purposes of digital agency. We register and administer domains (and SSL certificates) on behalf of our clients. After we do all the work, we invoice it to them together with all the costs for registration. Therefore no payment through payment gateway is needed as we only want to send pro bono invoice to client.

It seems that this system only works after payment has been successfully submitted. Unfortunately that's not the case for us - we need to do everything automatically without payment. All payments are proceeded manually on our side.

Could you please advise if there's any setting or way how to bypass payment gateway? Specially in case of registration and renewal of domains.

Thank you for any answer,

Lukas