If you have already tried the steps found here and are using a google voice number you will need to follow the below steps to validate your phone number:
1. Go To Profile (Located on your Right Hand Corner)
2. Under your cell phone number box click on the link to validate your number.
3. You should be receiving a call but your phone will not ring. Wait 2-3 minutes.
4. Log into your google voice account on the application or web.
5. Search your voicemails SPAM folder and find one from LionDesk.
6. Check the box next to the voicemail and click the NOT SPAM button.
Now you can receive calls from LionDesk
7. Please proceed with the steps: https://liondesk.zendesk.com/hc/en-us/articles/218544108-How-To-Verify-a-Phone-Number
Notes: This article also covers the steps if you are not getting a phone call from LionDesk during validation.