Please do not get one of those devices.
They rebroadcast out on the same frequency and that means passers by will end up using your frequency. This means your poor equipment at £25 ends up causing everyone around you issues as ultimately the performance of it will be nowhere near in line with the multi thousand pound equipment used at the official cell site.
There is also monitoring by cell sites for rogue devices & you could face a very hefty fine.
Use of this equipment would fall under the deliberate interference category. Here ofcom have come down heavily, with an unlimited fine and a conviction of upto two years imprisonment. This is necesssary because the impact can be huge, if somebody was to get one of these devices in central London, they could affect tens of thousands of users daily.
What you can do however is contact Vodafone for a Vodafone sure signal, this is legitimate and allows you to use your home broadband as backhaul for your calls.
Also if you have an iPhone you can enable WiFi calling to get calls over WiFi instead of the cell site. That said I am tipping you do not have an iPhone as these devices generally will not allow you to force only 2G due to the carrier settings not allowing it.
EDIT: sure signal and wifi calling will not work, you are not with Vodafone directly but an MVNO of VF. Only fix I can think of is to contact the provider and explain you have no signal despite being informed it would be the same as o2. See if they'll let you go.
Edited by ukhardy07 (Thu 24-Nov-16 01:29:29)