text: Media playback is unsupported on your device Media caption Taller masts across the rest of Britain can be fast-tracked through planning
  
  Wales could be left behind when the next generation of mobile phones arrives, AMs have warned.
  
  Faster download speeds will be possible when 5G networks are introduced, perhaps by the end of 2019.
  
  The assembly's economy committee says it should be easier to build taller masts which spread signals further.
  
  Restrictions on mast heights were relaxed in England and Scotland in 2016, but the Welsh Government said it would make the same changes this year.
  
  In the rest of Britain, masts up to 25m do not go through the full planning process under what are known as permitted development rights. The limit in Wales is 15m.
  
  The Welsh Government promised more than two years ago to look at the evidence before deciding whether to adopt the same rules.
  
  A report it commissioned said in December 2017 that the limit should be increased to 25m.
  
  But economy committee chairman Russell George said: "We've got not-spot areas across Wales. People are deeply frustrated.
  
  "The Welsh Government has got levers at its disposal that it can use. Not all the levers, but some levers.
  
  "One of the levers it's got at its disposal is changing the planning regime and they haven't done it."
  
  Image copyright Getty Images Image caption 5G promises much faster data download and upload speeds
  
  Mobile phone operators told his committee the limit should increase to 30m. They also say they are willing to share masts.
  
  More than half of Wales (56%) is covered by all mobile operators, up from 28% in June 2017.
  
  But the report says it is not clear whether the improvement is due to a Welsh Government mobile action plan published in October 2017.
  
  It says people should be allowed to roam between networks - and says the UK government should make it mandatory if operators do not allow it.
  
  Hand tied behind back
  
  Deputy economy minister Lee Waters said new permitted development rights would be introduced this year, "but it takes time to get these changes through".
  
  "Telecoms is not devolved - I wish it was devolved, in which case we could do more," he said.
  
  "At the moment we've got one hand tied behind our back and we are trying to do what we can."
  
  A Welsh Government spokesman said: "Wales' geography presents many challenges and we are taking action in the areas where we have responsibility through the Mobile Action Plan.
  
  "This includes developing mobile action zones across Wales to address stubborn mobile not-spots. We thank the committee for the report and will respond in detail in due course."
  
  There is no firm date for 5G, although AMs were told the industry could start introducing it in 2019.
  
  The next generation will offer faster download speeds on smartphones.
  
  Telecoms regulator Ofcom says the timetable depends on operators upgrading their networks.