Trevor Prideaux, who was born without his left arm, used to have to balance the smartphone on his prosthetic arm or put it on a flat surface to use it.
But now Mr Prideaux, 50, can call and text his loved ones without moving the mobile, which is embedded into his fibreglass and laminate limb.
The catering manager sought help from medical experts and communications chiefs at Nokia to build the special prosthethic.
They carefully carved a phone shaped fibrecast cradle into the skin-coloured prototype, allowing his Nokia C7 to sit inside it.
Mr Prideaux, of Wedmore, Somerset, said: “I think this is the first time this has ever been done in the world – and it is brilliant.
“I can now take calls and make texts just by using my one hand, while the phone sits inside my arm.”
“The phone slots smoothly and securely within my limb and is easily removable, when required. I think this would help a lot of people with prosthethic arms – especially those who were not born with the disability.
“People who have had motorbike crashes and soldiers who have lost limbs – they could all benefit from this.”
Mr Prideaux has worn a prosthetic limb since he was three years old after being born without a left forearm.
The father-of-one, who lives with his partner Amanda, has always had his limbs specially made at the Exeter Mobility Centre in Devon.
But since mobile phones – and in particular smartphones – became mainstream, the caterer found he struggled to text and make calls with one arm.
“When testing an iPhone, with the thoughts of purchase, I had to balance it on my prosthetic limb to text.
“I wondered whether it was possible to have a mobile phone built into my limb, to aid usage.
“I was born without my arm so I am used to adapting to things – but I thought that others must be struggling too.”
Trevor contacted Apple to try and get hold of a blank iPhone casing to test it out, but he said the communications giant refused to co-operate.
He then put the idea to the back of his mind, before a trip to his local 02 shop to get an upgrade on his Nokia phone brought the plan back to life.
They agreed to help him and his technicians at the Exeter Mobility Centre got working on a ground-breaking limb.
Prosthethist Steve Gallichan, technician Les Street and undergraduate worker Sarah Bennett then produced a prototype in just five weeks.
They made a laminated fibre cast of the phone and built it into the limb, so Mr Prideaux’s mobile could fit inside.
He said: “This phone is slightly narrower than an iPhone and has both a qwerty and alphanumeric board, which is easier for me to use.
“My Nokia C7 sits within my forearm, between my stump socket and the single knob rotary that holds my limb attachments in place.
“Now when I get call I can either hold my arm up to my ear or put it on speaker phone. I can also take it out if I need to. Texting is also much easier and a lot safer.
“I am hugely grateful to the people at EMC. This is a leap forward which has helped me out a lot and can also aid others.”