184Furthermore, it should be recalled that, in the context of the application of the 1998 Guidelines, which made a distinction between very serious, serious and less serious infringements, the Court confirmed the Commission’s assessment that the implementation of a practice of margin squeezing by an incumbent national telecommunications operator should be classified as a very serious infringement and a flagrant abuse of a dominant position (judgment of 29 March 2012 in Telefónica and Telefónica de España v Commission, T‑336/07, ECR, EU:T:2012:172, paragraphs 382 to 387). It should be added that the Court confirmed the classification of the infringement at issue as ‘very serious’ for the entire period of the infringement concerned, even though the Commission acknowledged that the gravity of that infringement was not uniform throughout that period (judgment in Telefónica and Telefónica de España v Commission, EU:T:2012:172, paragraphs 417 to 419).