Vodafone posted a sharp drop in quarterly organic growth as weak trading in Italy and unexpected slowdowns in Britain and India hit the world's largest mobile operator.
Vodafone shares were down 1.6% in early trading.
European rivals Deutsche Telekom and France Telecom also slipped as investors digested the update from the operator widely regarded as the strongest in the sector.
While Vodafone has outperformed peers in the past year, tough conditions across Europe forced it to cut its medium-term outlook and write down the value of assets by £4 billion in May, as customers sought to save money by making fewer calls and deferring handset upgrades.
The group reiterated its outlook today and said it would embark on a new wave of cost cuts, which analysts welcomed as a sign the group would protect its earnings.
Vodafone posted group service revenue of £9.98 billion in its first quarter to end-June, up 0.6% compared with a forecast for 0.9%. That was down from 2.3% growth in the group's fourth quarter, which benefited from the extra leap year day.
Vodafone said it was hit by weak consumer confidence in Italy and Spain, the poor economy and increasing competition in Britain and a slight slowdown in India. Its corporate unit was also hit by less demand from small and medium sized businesses across Europe.
India posted a slowdown from a strong fourth quarter where it had good year-on-year customer growth, while its infrastructure unit of Indus Towers also slowed.
Service revenue grew by 16.2% in the three months to the end of June, 4.9 percentage points lower.
"Despite the difficult market conditions, particularly in southern Europe, we continue to make progress in the key areas of data, enterprise and emerging markets, while maintaining tight control of our cost base," Chief Executive Vittorio Colao said.
In the first quarter, organic service revenue growth in Europe was down 1.6% while the emerging markets division was up 6.1%.
In a statement, Vodafone Ireland said it had a "total customer base of 2.44 million at the quarter ended June 30, 2012."
This is an increase of 0.5% year on year.
