The company, which is currently incorporated in Jersey, traces its origins to Ireland's former state-owned monopoly telecommunication provider Telecom Éireann and its predecessors, P&T (the Dept.

Eir is currently majority owned by Xavier Niel's Iliad SA and his Paris-based NJJ Telecom Europe investment fund (64.5%).

SIRO operates a FTTH network using ESB's physical infrastructure to carry fibres to individual homes and businesses.

These offer ample and affordable data plans and very high speeds and a number of operators have designed products targeting homes and businesses using both existing mobile and dedicated LTE and 5G networks.

Eir operates the largest fixed-line telecommunications network in Ireland, under licence from the Commission for Communications Regulation (ComReg).

The company has used EDGE technology on its network and has received a 3G (UMTS) license, formally removed from Eir's competitor, Smart Telecom.

(This article deals mainly with the post-privatisation Eir; for details of the company during its time as a state-sponsored body, see Telecom Éireann.)

Many of the 500,000 small investors were angered by the significant financial loss they incurred, blaming the government for not sufficiently warning them of the risks inherent in stock-market investment.

On 9 July 2005, The Irish Times reported three bidders for Meteor: Eircom, Smart Telecom, and a consortium led by Denis O'Brien.

On 14 July 2005 RTÉ News reported on their business website that Denis O'Brien had withdrawn from bidding, and that it was understood that Eircom was the top bidder at €410 million.

[12] As of 31 December 2012, Meteor had over 1,086,000 customers and a market share of 20%, offering both GSM and 3G mobile telephony and broadband services.

[13] In May 2006, Eircom announced its sale to the Australian investment group Babcock & Brown as part of a deal worth €2.4 billion.

The same day, Phillip Nolan resigned as chief executive of Eircom, and on 1 September Rex Comb was officially named as the new CEO.

Tony O'Reilly resigned as chairman and was replaced by Pierre Danon, previously of BT Group plc and JP Morgan Chase.

Babcock & Brown have since collapsed as a company and their BCM vehicle, which owns over 50% of Eir, broke all ties with the former parent and rebranded themselves as Eircom Holdings Limited.

[15] In September 2015, Eircom announced that it would re-brand as eir as part of a new imaging campaign developed by Moving Brands.

Described as being "dynamic and modern", the new brand was adopted across most of Eircom's businesses (excluding Meteor), and an advertising campaign was introduced to promote the new name and slogan, "Live life on eir".

As Eircom, Eir joined a consortium with TV3 Group, Arqiva, and Setanta Sports called OneVision to apply for the Commercial licence for DTT.

[21] Eircom notified the public in February 2012 that they had decided to no longer honour their debt, had entered default status and would not continue as a going concern.

Eircom gave notification that they had cancelled a mandatory interest payment on their publicly-traded senior corporate bond, then due to mature in 2016.

On 29 March 2012, a number of companies within the Eircom Group presented a petition to the Irish High Court for the appointment of an examiner.

[27] After the privatisation of Telecom Éireann, the highly profitable mobile phone division, Eircell, was sold to Vodafone.

[34] On 21 April 2008, Eircom rejected claims by four major record companies that it, as the largest broadband internet service provider in the state, must bear some liability for the illegal free downloading of music by computer users.

This in turn raised concerns over internet privacy, since presumably this would be enforced through the monitoring of IP traffic associated with Eir's customers.

As of 5 December 2013, Eir users who try to access The Pirate Bay receive the following message: Eircom agreed to a controversial deal with the IRMA to activate a "three strikes system" so that users would be banned from the Internet for seven days if they appeared to be downloading copyrighted content through peer to peer filesharing networks.