Apparently, Barablu, a WiFi-oriented mobile VoIP provider, has been named by Ofcom as one of only two eligible bidders for a slice of GSM spectrum in Northern Ireland.
Now, I haven't delved into the details of that spectrum award, but I wonder if this is a similar pitch to Truphone's in the UK - get recognised as a "mobile operator", get a cellular number range.... but don't build a cellular network. Instead, just use WiFi wherever possible, and benefit from the inbound interconnect fees levied on other operators for terminating calls on those mobile numbers.
Obviously this would only work if there was some pretty lax definitions of both the coverage requirements of the licence, and the interconnect regime for calls to mobile numbers terminating via non-cellular mechanisms.
On the other hand, maybe they do want to deploy a proper cellular network, or a femto/picocell-based one.