Currently this tield type is using a field type of text for the phone field instead of tell so the mobile user has to switch to the number keyboard then type the number by using the horizontal number keyboard. Switching this field type to type=tel will bring up the dial pad with big number making it much easier for the user to enter their mobile number.

Also when you tap in the fields in the chat widget it auto zooms in causing the form to go off the screen and messing with the mobile website after submitting the form which make the user have to pinch and zoom to get the mobile site looking back right.

Disabling this autozoom would be greate also. I have done this on forms by increasing the text input font size to over 16px I think or adding some viewport meta code in the header.