Andrew Acoyne wrote a good opinion piece in the Vancouver Sun ...
Here is a list of some of the things we do not know about the Robo con scandal (the use of auto-mated "robocalls" to harass or deceive - con - voters in certain riding). We do not know whether the calls were made by members of the Conservative party. We do not know whether any Conservative authorized them, or even knew about them. We do no know whether anyone was pre-vented from voting, or had their vote changed, as a result, nor do we know whether the results of any riding were affected. But my God, what we know is disturbing enough. Read more: http://www.vancouversun.com/news/Conservatives+fought+hard+their+majority+perhaps+hard/6209387/story.html#ixzz1nOvHLmlN
Generally only two sources have this kind of information on such a massive scale. Polling/voter contact companies and political parties. Companies that did voter contact for the Conservatives would have this information. It is possible that a company that did calling for a political party could have had their records accessed for the purpose of these robo or live call. The company may or may not be aware these records were accessed.
I have worked campaigns in various capacities, either as manager or in some other significant role. I am familiar with the NDP voter ID program, at least as it was several years ago. The data was stored by a company in Regina. It is accessed over the net and local campaigns guard that info very closely. You can only access your local riding information. Its use for other than legitimate political reasons is illegal. I expect the Conservatives voter ID database is similar, perhaps even better.
To get the data for more than one riding you have to work with others. One person could not do this on his own unless he was given full access. The ridings targeted for the live and robo calls were all considered swing ridings. Harper's election victory was 14 seats, coincidently 14 ridings received live calls, purporting to be from the Liberal party where the callers were rude, calling often and either very early in the morning or late in the evening. From my own experience with the NDP we never called people before 10am weekdays, before noon on Sunday or after 9pm. Calling after or before those hours just ticks people off. The desired effect was to turn voters off from voting. Voter suppression.
Back to the data. To use party data from inside the party, you would have to be the one in charge or a trusted individual with access. You would then have to take the data, which is against the law, and then provide it to at least one other person to do the calls. In the case of the live calls, its clear that many more people were involved. Thousands of calls were made to 14 or more ridings. This suggests a great deal of planning and co-ordination.
The other means of doing this without an official party worker would be if a company used to to do voter contact did it on its own. They keep the information and either do the calls themselves or provide them to someone else to do the calling. The Company's motivation is clear, they work for the party and by doing this they avoid linking the Party directly. Nudge nudge, wink wink!