The following offers a review of some of O2's key business highlights since demerger from BT in November 2001.
11 July 2008: Apple iPhone 3G launches in the UK and Ireland, exclusively on O2.
2 July 2008: O2 and Live Nation announce The O2 in Ireland.
27 June 2008: The O2 in the UK celebrates its first birthday.
17 April 2008: Telefónica O2 UK launch mobile broadband service.
28 February 2008: Apple iPhone launches in Ireland, exclusively on O2.
9 November 2007: Apple iPhone launches in the UK, exclusively on O2.
3 October 2007: O2 launches new broadband service to the UK market.
1 October 2007: Telefónica and Yahoo! partner to bring global mobile services to more than 100 million customers.
18 September 2007: Apple chooses O2 as exclusive carrier for iPhone in the UK.
30 August 2007: Telefónica launches 'Fonic' discount mobile service in Germany.
26 July 2007: O2 introduce full Eurotariff to bring down prices of incoming and outgoing calls in the EU countries and Ukraine by more than 40%.
9 July 2007: O2 Ireland launches broadband service.
19 April 2007: Telefónica sells Airwave to Macquarie for €2,982 million.
7 March 2007: O2 first mobile operator in Ireland to trial broadcast mobile TV, in partnership with Arqiva.
2 February 2007: O2 Airwave awarded London Underground contract.
24 January 2007: O2 enters its fifth European market with Slovakia.
23 October 2006: O2 and Arqiva to commence first consumer trial of broadcast mobile TV in Ireland.
18 October 2006: O2 and Movistar offer free incoming calls when travelling in Europe.
1 September 2006: O2 launches in the Czech Republic.
2 August 2006: Telefónica O2 wins tender for 3rd mobile licence in Slovakia.
20 June 2006: O2 enters UK broadband market with purchase of Be.
11 May 2006: O2 and Telefónica Móviles announce 'My Europe' - delivering significant roaming benefits for customers.
28 April 2006: Integration of Czech Republic businesses approved. Peter Erskine becomes Chairman of supervisory board.
30 March 2006: O2 Airwave awarded £350m Fire & Rescue services contract.
7 March 2006: O2 de-lists, from the London Stock Exchange, on completion of the take-over by Telefónica S.A.
6 March 2006: O2 Germany records 10 million customers.
1 March 2006: Eurotel and Ceský Telecom are joining forces to create the telecommunications company of the future.
23 January 2006: O2 announced best ever quarter customer growth in the UK and Germany.
23 January 2006: O2 announced new Board and Telefónica S.A. cash offer went unconditional in all respects.
13 January 2006: O2 Germany became official partner of the BMW Sauber F1 Team.
29 December 2005: Tesco Mobile announced one million pre-pay customers.
11 November 2005: Firelink, the procuring body for the national communications contract, confirmed that O2 Airwave has been successful in the bid to equip all fire and rescue services across England with a new resilient and secure voice and data communications service.
26 September 2005: O2 announces UK launch of i-mode®.
22 September 2005: Mobile TV trial goes live in Oxford, UK.
19 July 2005: O2 Airwave announces that it has been successful in its bid to provide a communications service to all Ambulance Trusts in England.
25 May 2005: O2 and Anschutz Entertainment Group unveil 'The O2' and sign exclusive mobile content and music deal.
14 April 2005: O2 becomes the first UK-based mobile operator to gain ISO 14001 environmental certification group-wide.
1 April 2005: O2 Airwave completes its network roll-out to provide every police force in England, Scotland and Wales with state of the art, secure digital communications.
14 March 2005: O2 plc lists on London Stock Exchange following corporate reorganisation.
12 January 2005: Corporate reorganisation to create distributable reserves announced.
29 November 2004: mmO2 and NTT DoCoMo announce agreement on i-mode.
17 November 2004: New policy of regular, sustainable dividends announced.
15 November 2004: Hereford and Worcester Ambulance Service celebrate saving their 100th heart attack patient using O2 Airwave technology.
12 July 2004: O2 Germany and Tchibo set up joint venture.
18 May 2004: Group reports first pre-tax profit of £95 million. (After goodwill and exceptional items)
28 April 2004: Highways Agency signs up for Airwave.
21 March 2004: O2 Germany launches 3G.
23 February 2004: O2 joins Starmap Mobile Alliance, a union of ten leading mobile operators.
4 February 2004: O2 Airwave provided to more than 30 police forces.
17 November 2003: O2 Online signs up its one millionth customer.
15 October 2003: Airwave delivered to more than 50% of the UK's Police Forces.
24 June 2003: O2 Germany tops 5 million customers.
4 June 2003: O2 UK and Tesco create Tesco Mobile joint venture.
3 June 2003: Sale of O2 Netherlands completed.
31 March 2003: Airwave rolled-out to 10 police forces.
28 March 2003: MMS interconnect with Orange, T-Mobile and Vodafone in the UK.
4 February 2003: Agreement with T-Mobile to extend co-operation on rollout of 3G mobile networks in Germany.
3 February 2003: Ireland Wireless Lan commercial service launched.
5 December 2002: Can Do in the Community Programme launched.
19 November 2002: Germany EBITDA positive - a year ahead of schedule.
18 November 2002: O2 UK breaks text messaging record.
31 October 2002: MMS launches.
28 September 2002: Launch of Java Games.
18 June 2002: xda from O2 on sale in UK and Germany.
24 May 2002: O2 Germany tops 4 million customers.
1 May 2002: Launch of O2 consumer brand.
16 April 2002: mmO2 appoints Nortel & Nokia as principal group-wide network suppliers.
11 April 2002: O2 UK signs 10-year strategic IT management agreement with IBM.
13 March 2002: Lancashire becomes first UK fire brigade to adopt Airwave service.
15 January 2002: mmO2 successfully completes £1bn bond issue.
5 December 2001: Europe's first fully operational 3G network goes live on the Isle of Man.
19 November 2001: mmO2 demerged from BT to become an independent wholly owned company.
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