You have to follow this guide for both ArquatiPBX (52.57.247.41) and ArquatiPBX_bkp (35.156.113.252)

First, you need to turn on the backup server.
You can do this on AWS by clicking on this link.
Once the page is open, search for the ArquatiPBX_bkp server, select it, click on the Instance State button


and select start instance.

1. Open the sysmgmt, click on Phone System > Trunks and click Asterisk2
   
2. Click on the Access Numbers section and choose a number. You will use this number as an example to copy the next configurations.
   The following photo is only an illustrative example.
   

Follow this step for both ArquatiPBX and ArquatiPBX_bkp

1. Click on FreePBX Administration and login
   
2. Connectivity > Trunks and search for the number you chose during the preparation step
   
   
   The following photo is only an illustrative example.
   
3. Click on the modify button in Action section and press Duplicate
   
   
4. Now replace the number in the copy with the one given to you by Arquati (don't forget to keep the +39 in Outbound CallerID).
   Be sure to check the other sections as well to replace it
   
5. Connectivity > Outbound Routes, ctrl + f and search for the number you chose during the preparation step
   
   
6. Click on the modify button in Action section and press Duplicate
   
   
7. Now replace the number in the copy with the one given to you by Arquati.
   Don't forget to change these trunks with the one you created ).
   
   Be sure to check the other sections as well to replace the number
   
   
8. Connectivity > Inbound Routes here there is no way to duplicate an existing inbound route, so you will need to copy it manually (you could open two windows to copy it easily).
   
   
9. To create a new Inbound Route click on Add Inbound Routes
   
10. Now copy the entire configuration, making sure to change the number with the one provided by Arquati.
    Make sure to change Set Destination by selecting the Trunks option and choosing the trunk you created earlier.
    
    Be sure to check the other sections as well to replace the number and set the right configuration
    
    
11. And MOST IMPORTANT click on Apply Config to save your changes
    
12. Lastly, add the number on the sysmgmt and test it