As SIS Live are responsible for the OB sections providing the satellite uplinks,cameraman and getting the pictures back to ITv I believe they have a corporate account with Vodafone so expect it will be Vodafone 4G.
Although as quite a high profile thing EE may have offered to provide theirs for free especially as they have recently been doing a trial with Sky News and Sky sports using 4G for broadcast its a device that can link upto 4 connections together into one transport stream for HD broadcast with over 150meg upload i think the connections also have some special QOS/ network priority procedures added by EE as well.i have seen it in action and really can not tell the difference what is uplinked using 4G and what's by satellite truck.
There are other 3rd party systems out there using 4G but they tend to use normal sims and try to bond the connection which often isn't seamless so end up with choppy playback where as EE provide,monitor and control things from their end. I think they see it as another revenue provider and can offer it quite widespread as long as in 20mhz areas.