Using Wifi on T27G with iPhone Hotspot

I am trying to setup my Yealink T27G with the wifi dongle and my iphone as the internet source. However when I try to connect to my hotspot on the phone, it refuses to make the connection. It just spins and then backs out of the connection process. Is there a reason that I cannot connect to a hotspot on my phone to provide the internet in an emergency? Is a software update required on the T27G to allow that to happen? I know the wifi dongle works because it allowed me to connect to my office wifi, however I can’t do the hotspot. What is the problem?

Does your iPhone service provider allow hotspots? Some have an extra fee to allow that.