Adding SIP trunk to Elastix system (2.3)

I have a SIP Trunk for Saudi Telecom Company (STC) in Saudi Arabia and I want to configure inbound and outbound calls. The SIP trunk comes with static IP address and its connected directly to the STC company. I need an expert who did this STC SIP trunk connection many times. I need him/her to send me the full configuration steps so I can do it. Note: 1- I can Not let you access the Elastix server so Please do not ask for that. 2- The line must detect when the user answers the calls and when the user hang up