That's why for any office that has internal wifi I encourage also having a "guest" wifi network (small offices, not using anything with enterprise-level management). People are going to want to connect devices to wifi instead of LTE even if they never approach their billing limits, and if there's an available option that they're allowed to use it cuts down on attempts to use the one they're restricted from (and complaints about "I tried to connect to the wifi but I can't get to the Internet!" "Was it the internal one or the guest? Internal is locked down. Connect to the guest.")