Update Sandbox whitelist guide for new whitelist version

gettingstarted/sandbox/whitelist.md

@@ -12,6 +12,16 @@ Check the [Privacy](/docs/privacy) guide for more information on why Open Gatewa
 
 ## Adding your mobile lines to the whitelist
 
-In order to add your lines to the whitelist, just fill-in the text fields at the bottom of the [production environments access application form](https://opengateway.telefonica.com/en/sandbox/registration). Our Developer Hub support team will review your request and will get back to you with the confirmation of the addition of your lines to the whitelist.
+In order to add your lines to the whitelist, just visit the Sandbox web console's section "My phone numbers", add your line's number and follow the Sandbox directions.
 
-In coming releases, you will be able to manage your whitelist from the Sandbox console.
+You will find a QR code to scan with your mobile device. Be sure to use the device in which the line's SIM card is installed. Since the goal is to verify the line is yours, you need to be connected by using the line's data. If your device is connected to a WiFi or your device is dual SIM and it is using the other line's data, the operator won't be able to verify it. Check your device mobile settings in that case.
+
+![Verify a new line capturing a QR code](https://github.com/Telefonica/opengateway-developers-website/raw/main/gettingstarted/sandbox/images/whitelist-qr.png?autoSizes=true)
+
+Your mobile device will be redirected to a web page which will use the Number Verification API itself to verify the line. Once the verification is done, your line will be added to the whitelist, and you will find it as verified on the "My phone numbers" section in the Sandbox web console.
+
+![Complete verification on your mobile device](https://github.com/Telefonica/opengateway-developers-website/raw/main/gettingstarted/sandbox/images/whitelist-mobile.png?autoSizes=true)
+
+In case you get your line added but you didn't get the verification done, you can try again by clicking the QR icon next to your line in the "My phone numbers" section to trigger the verification process again.
+
+![Resume verification from the white list](https://github.com/Telefonica/opengateway-developers-website/raw/main/gettingstarted/sandbox/images/whitelist-verify.png?autoSizes=true)