By Stephen Mulvey
EU reporter, BBC News
EU efforts to cut mobile roaming costs by summer have been thrown into doubt because MEPs and European governments cannot agree on the details.
MEPs and member states could run out of time
Attempts to reach a compromise before a vote originally scheduled to be held in parliament next week have collapsed.
The vote has now been delayed and the timetable for securing a deal before the holidays is getting very tight.
MEPs and ministers have differed on how high to fix the price, and on whether all users would benefit automatically.
A compromise package put forward by parliamentary negotiators on Thursday set the maximum cost for making an international call on a foreign network at 45 euro cents (30p) and 20 cents (14p) for receiving a call, per minute.
PROPOSED ROAMING CAPS
Making a call
Parliament opening bid: 40c European Commission: 44c Parliament compromise: 45c German EU presidency: 60c Industry (GSMA): 65c
Receiving a call
Parliament opening bid: 15c European Commission: 15c Parliament compromise: 20c German EU presidency: 30c Industry (GSMA): 35c
Charges per minute, excluding VAT
The German government, representing EU member states, has proposed caps of 60 cents and 30 cents respectively.
Many consumers currently pay one euro (68p) per minute, to make a call abroad.
Opting in and out
Up to now MEPs have also insisted that the new "consumer protection tariff" should apply automatically to all telephone users, unless they opt for an alternative package.
Governments have favoured an opt-in system.
The parliament's proposed compromise suggests introducing an initial period of three months during which consumers would have to opt in to benefit from the new tariffs.
After that they would be transferred to the new tariff automatically, unless they opted out.
Instead of voting on the regulation next week, the parliament is now expected to vote in the week beginning 21 May, which leaves two to three weeks for the two sides to come to a final agreement.
The member states could give their final approval at a meeting on 7 June, which would allow the regulation to come into force some time in July.
But any further hitches along the way would see the holidays come and go before any new charges could apply.
Some governments, including the UK, have argued that the European Parliament and European Commission are setting the price cap so low that telephone companies may respond by increasing the cost of domestic calls.
The UK is also in favour of a full opt-in system.
"An inflexible proposal which denies mobile phone users choice and could lead to much higher charges on our subsidised handsets is not on," British Industry Minister Margaret Hodge was quoted as saying on Thursday.