The phone’s SIM signal has been monitored ever since he went missing, and it was traced for the first time on Thursday night to an area which was narrowed down to the city of Edinburgh.
It is believed that Mr Brahney, 22, left Heaton Park with friends before returning to try and find the mobile at around 11.30pm on Friday, June 29. He has not been seen since.
Mr Brahney’s close friend, James Broxup, contacted the Evening News to urge anyone who has seen his friend or the phone to come forward.
“The police think his phone is in Edinburgh, whether he is or not, nobody has a clue. But even if someone just has his phone it would be useful to the police to speak to them.
“It’s been a week – they need anything they can.”
A description of the handset has not been issued, but Mr Broxup said he believed it was a dark Sony Ericsson model.
Mr Broxup, 23, who met Mr Brahney at university in 2007 added: “He didn’t have any links to Edinburgh and I don’t think he had friends there. But the police have said nothing can be ruled out because there was a park and ride site with loads of buses.
“Chris is very funny, friendly and good natured. I never saw him get aggressive or angry. He gets on with everybody.
“To disappear is definitely not the type of thing he would do. He would have been in touch, it’s very odd.”
The Stone Roses, Stephen Fry and Rio Ferdinand are among the celebrities who have made public appeals. Police are also chasing leads following reported sightings of Mr Brahney.
Detective Inspector Debbie Oakes of Greater Manchester Police said: “Chris’ phone may be in Edinburgh. This is the phone that Chris was trying to find when he went missing. At this stage all indications suggest that someone else now has this phone. I would urge that person to come forward.
“I want to reassure him or her that they are not in any trouble. All we are interested in is what they know and they may well have information that is vital to this inquiry.”