The debut series of reality show Big Brother on Richard Desmond's Channel 5 in 2011 was first UK television programme to invite viewers to pay to vote via Facebook, alongside the standard phone vote system.
Viewers could purchase votes via the Facebook Credits system, with each credit buying one vote at a cost of around 6.5p (although they were sold in blocks with a minimum spend of 65p).
During the Big Brother: Live Final aired on November 11 on Channel 5, host Brian Dowling repeatedly invited viewers to vote either via Facebook or phone. But seven complainants contacted Ofcom to claim that they were unable to access the Big Brother Facebook page during the final stages of the voting window. This meant that they were unable to place votes that they had already purchased.
In response, Channel 5 explained that during the final ten minutes of the voting window, the server hosting the Facebook voting system was "temporarily overloaded due to exceptionally high traffic levels across the entire Big Brother application (i.e. not just traffic from those wishing to vote)". This meant some Facebook users were "unable to vote expediently or at all".
The incident was first reported at 9.48pm and Channel 5 ran a series of tests two minutes later with its service provider, but a remedy was not found until after the voting window had closed.
Channel 5 denied that it had misled the viewers, claiming that it was "not liable for any Facebook votes not being registered or recorded due to the technical failure it had with the server".
However, it pointed out that it had offered anyone with remaining votes to use them in the subsequent Celebrity Big Brother series broadcast in January 2012, or refunds would be offered "upon reasonable request within a reasonable timeframe".
The broadcaster responded to the incident by increasing the server capacity "sevenfold" for future Facebook voting, meaning it was "confident that this level of capacity exceeds the expected traffic throughout the forthcoming series".
After Channel 5 passed Big Brother voting information to Ofcom, the regulator said that it was "satisfied that the problems experienced on the Facebook application server would not have affected the outcome of the vote".
Ofcom noted that because this is the first time that Facebook voting had been used in the UK, there were "elements of uncertainty about its operation and demand for the service".
The regulator said that it was "concerned" that Channel 5 had not upheld its licence-holder responsibility to ensure that all audience voting systems were "sufficiently robust" to deal with demand, but accepted that Channel 5 did not "deliberately" intend to mislead viewers about the Facebook voting process.
Ofcom praised Channel 5's offer for any remaining votes to be reused or refunded, and welcomed the move to increase server capacity for future Facebook voting.
"Ofcom also noted the action undertaken by Channel 5 to improve the speed at which any such incidents would be identified and reported," said the regulator. "Taking these actions into account, Ofcom considers the matter resolved."
Ofcom is currently running a year-long trial of allowing broadcasters to offer paid-for viewer participation for audience voting and competition schemes using web-based applications, such as social networks.
After the trial ends on August 20, 2012, Ofcom will asses the impact of associated issues around the scheme, but it said that in light of the Channel 5 case, it "may decide to undertake a more wide-ranging formal review of this area".