I work on the Elite x3 Support team. You would need to purchase the CDMA unit that is sold to work on the Verizon network. Your Elite x3 was sold to work on the GSM network (AT&T or TMobile). There are only 3 Part numbers sold for Verizon: 1PK92AA, 1PK93AA. 2CF73UT.
I noticed that the HP X3 is now compatible with Verizon CDMA networks. Do you know what was done to the phone to make it work on Verizon? I have a Nokia 950 XL. Is this a software upgrade? I would be happy to pay for it if it would get my 950 XL to work on Verizon