Just upgraded on Virgin from old Samsung Core to Samsung Galaxy prime. Virgin call handler said that if I paired the new and old phones via Bluetooth the contacts list on my old phone would be transferred to the new phone. Hasn't happened. Tried to phone up for advice but after a couple of minutes the conversation went dead and call reverted to the Virgin "introduction" on 789.
When I went from a Galaxy S2 to an S5 I used the Samsung Smart Switch app to transfer everything across to my new phone.
Disclaimer - I don't work for Virgin Media. I'm just another VM user trying to help out so my answers may be wrong :-) If you do like my answer please mark it as helpful as it may help others My setup: Vivid 200 Optical fibre with Superhub 2 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.