Tethering requires USB drivers to be available for the host OS to make use of the Jetpack as a tethered device. It is very unlikely that someone has USB drivers for the 7730 jetpack for your iPhone OS.
The list of drivers available for tethering can be found on Verizon's support website. In my experience those options have been limited to Windows and Mac Desktop OS's.
I would highly recommend using the WiFi feature of your Jetpack to connect to your iPhone. Otherwise you are lugging around your phone with a large battery pack attached to it.
carman5912, I want to make sure that you are set up for success when you are using our products such as for tethering with your MiFi 7730 Jetpack and iPhone X. As John Getzke mentioned, this Jetpack device would not be capable to tether directly to the iPhone X as it does not have a capable USB driver to handle this type of feature. Can you tell me what you wanted to accomplish by tethering your Jetpack to your iPhone X? Is your iPhone X currently active on your Verizon Wireless account?
Follow us on TWITTER @VZWSupport
If my response answered your question please click the _Correct Answer_ button under my response. This ensures others can benefit from our conversation. Thanks in advance for your help with this!!