[4] In 1995, the government, with Michael Lowry as Minister for Transport, Energy, and Communications, authorised a second mobile phone network, to compete with Eircell owned by the semi-state Telecom Éireann.

[5] On 23 March 2009 Vodafone and O2's parent company Telefónica announced a deal to share their existing networks in Ireland and rollout future infrastructure jointly.

[7] On 24 June 2013, it was announced that Hutchison Whampoa would acquire Telefónica's Irish mobile operations for €780 million, to be merged into 3 Ireland upon completion of the deal.

However, in early 2008 they introduced a new tariff which offered unlimited free text messages to all networks at any time, for life.

In 2010, O2 underwent a restructuring phase, implementing a number of cost-cutting measures which involved outsourcing internal divisions to external companies.

Another high-profile sponsorship agreement was their association with the Irish Rugby Football Union and the Ireland national team, which has been continued by Three.

[15] Hanway first joined Telefónica in Ireland in 2005 as Head of Customer Care, subsequently becoming Consumer Sales Director.

Immediately prior to taking the role, Hanway headed up the Consumer division of Telefónica in the Czech Republic, managing a team of over 4000 people across the retail, online and customer care functions.

[16] Analysis by the Sunday Independent in January 2006 showed the massive margins being earned by Vodafone and O2 in the country were costing Irish mobile phone users about €300m a year.

If the mobile phone companies were to cut their Irish margins to the group average, O2 customers would end up paying €84.07 less every year (€7 a month less).

[19] The next month O2 customers got a busy signal or no dial tone at all when they tried to make calls due to a network glitch.

The reason for the glitch remained a mystery at the time because the company's spokesperson couldn't be reached by the media on her mobile, also seemingly affected by the problem.

[20] The Consumers' Association of Ireland lodged a complaint with the Competition Authority over a loophole used by O2 that allowed it to bombard customers with unwanted text messages.

[21] The telecoms lobby group ALTO criticised O2 Ireland for its decision to quadruple the revenue it generated from calls to the 1850 LoCall number.

The company was criticised for its monthly subscription fees levied on Irish users of the iPhone, as they represented poor value for money when compared with the services available to customers paying similar amounts in the UK.

[26] O2 was responsible for the highest number of registered judgments, which financially blacklists those people who do not pay their bills on time in August 2008.

[28][29] In August 2010, O2 was warned by the telecoms watchdog, ComReg, that it could not move customers to online billing without their explicit agreement.

[31] In March 2011, it was revealed that Denis O'Brien made payments to the Minister for Communications, Michael Lowry, to aid Esat Digifone's licence bid.