The UK government could turn to mobile marketing technologies in an effort to get on top of immigration control.
Among measures proposed by the Home Office, visitors to the country would receive a text message reminding them when their visa is due to expire.
A Home Office spokesperson told AP the messages would be similar to those sent by banks to customers whose accounts are about to be closed.
A three-month trial is reportedly due to begin in April, but shadow home secretary David Davis criticised the idea.
"It is all rather extraordinary," he said. "The idea that somebody who is about to overstay or who is overstaying will change his mind because somebody sends him a text message seems to be something out of this world."
He said the government would "spam them with text messages" rather than deal with illegal immigrants properly. But home secretary John Reid said the SMS plan was a "tiny" element among wider reforms.