So Who Bought the Data?

I could be missing something here, but as T-Mobile has been outed (or perhaps, to be fair, has outed itself), as the mobile network whose staff have been allegedly selling on its customers details to other companies so they could try to persuade them to switch networks, the question Im asking myself is, should the companies buying the data not have been asking a few questions about where such potentially lucrative information had been obtained?
I have no idea who the brokers who allegedly bought the information sold it on to. The Information Commissioners Office (ICO) statement talks about the information being sold on to the service providers competitors, whose agents were using the material to cold call customers prior to contract expiry dates to offer them an alternative contract.
I dont know enough about the mobile phone distribution chain to hazard a guess at how many companies the all-embracing competitors might cover, but if any of the other UK mobile networks are found to have bought the data without seeking proper reassurances about its provenance, then this scandal could spread way beyond T-Mobile.
And with the telecoms regulator warning that, in light of the scandal, licences could be in jeopardy when they are due for renewal, who knows what implications the scandal could have for T-Mobiles proposed merger with Orange.
T-Mobiles actions in approaching the ICO once it realised what was happening are to be applauded, but this is looking like it could turn into a bad day at the office for the mobile industry.

David Murphy