Two children have taken their battle against phone masts near their school to the Court of Appeal.
Phoebe St Leger-Davey, six, and James Harrison, seven, want a High Court decision allowing a mast near their Winchester homes reviewed.
The hearing could influence 12,000 similar cases including an appeal against a mast near three schools in Harrogate, Yorkshire on Friday.
The judges reserved judgment after hearing a day of submissions.
The two children - acting through their mothers - went to the High Court seeking to overturn the decision to give the 11.79 metre high mast in Byron Avenue the go-ahead.
But the judge ruled that radiowave emissions fell within international guidelines, and there had been no procedural or legal flaw in the decision-making process.
David Wolfe, representing the children, told three appeal judges it was government policy to promote the infrastructure of mobile networks while minimising environmental impact and health concerns of the public.
"This policy states that planning authorities should work with mobile phone operators to find the optimum sites for masts and that health considerations and public concern should be taken into account," he said.
Christopher Katkowski QC, for Orange, said the reality of the case was that if the appeal was won, operators would be obliged to go to court every time they wanted permission for a mast to prove that there was no reasonable alternative to the site on the application.
Both sides must now await a decision by the judges.