Phone maker BlackBerry is investigating a problem which has affected users in Britain, elsewhere in Europe, across the Middle East and in Africa.
Blackberry developer Research in Motion gave few further details, but phone companies whose customers use the smartphones said that internet access and BlackBerry's popular messenger service appeared to be affected.
T-Mobile UK said in messages posted online that there was an "issue with sending and receiving via the BlackBerry Messenger service as well as using BlackBerry internet services".
It said that it and Research in Motion was looking into the matter.
The PA, photo by iNono