EU anti-trust chiefs have asked five European telecoms giants to answer concerns over possible industry collusion.
A European Commission spokesman told AFP it had sought answers on "the manner in which standardisation for future services in the mobile communications area is taking place."
This followed what the Financial Times said was periodic meetings since 2010 between bosses of Deutsche Telekom, France Telecom, Telefonica, Vodafone and Telecom Italia.
Brussels said the mobile industry association, the GSMA, had also been contacted.
No formal investigation has been launched at this stage, stressed Antoine Colombani, spokesman for European Union Competition Commissioner Joaquin Almunia.
"These fact-finding steps do not mean that we have competition concerns at this stage, nor do they prejudge the follow-up," he said in a subsequent statement.
Nevertheless, such requests do usually signal the preliminary stages of more detailed probes.
One source close to the case said questions focused notably on advertising platforms conceived for smartphones, or payment services via mobile phones.
The Commission is responsible for ensuring transparency across markets.
According to the FT, the so-called "E5" meetings addressed topics that included challenges posed by US groups such as Google and Apple and harmonisation of technology platforms.
Deutsche Telekom said in a statement after the EU confirmed it was looking into the meetings that the talks going back to 2010 focused on ideas to boost "growth and innovation" in Europe's digital sector, and so "contribute to growth in the EU."
The company said that the relevant authorities are routinely informed of such activities, and said the EU needed to send "a clear signal" that it would help indigenous European internet companies compete with the likes of Google, Apple and Amazon.
Telecom Italia chief Franco Bernabe also insisted that "maximum transparency" had "always" been shown to EU anti-trust authorities.
France Telecom and Telefonica refused to comment, while Vodafone simply acknowledged receipt of the Commission's questionnaire.