Trading in Europe has been cited by Vodafone as "tough" as the company revealed its latest financial results.
Data for the first half of the year showed that the firm made a pre-tax profit of £1.5 billion.
Chief executive Vittorio Colao explained that the company has experienced "intense macroeconomic, regulatory and competitive pressures during the period" in Europe.
Emerging markets were cited by Mr Colao as performing well for the company, which is one of the largest mobile phone operators in the world.
Mr Colao also called for the introduction of new regulation in order to support industry investment and consolidation.
Vodafone is now planning to concentrate on improving efficiency to boost its business in the coming months.
In the early stages of trading this morning (November 12th), the share price of Vodafone was down. At 08:13 GMT, its stocks had fallen by 0.51 per cent to 226.20.
This is still within reach of the company's 52-week high of 233.70.
Find up to date information on the FTSE 100 and spread betting strategies at City Index