For years mobile networks have been using a complicated algorithm to protect your phone calls being tracked and eavesdropped.

However Karsten Nohl and other experts have spent the last five months working to crack the code, and they now have.

Their work is said to show the weakness in the popular GSM security standard that 4bm mobile phone users rely on.

The findings could allow criminals and others to begin listening to your conversations.

Mr Nohl told the Chaos Communication Congress in Berlin that the work showed that GSM security was "inadequate".

He also stated:

"We are trying to inform people about this widespread vulnerability," he told BBC News.

"We hope to create some additional pressure and demand from customers for better encryption."

There is debate over the legitimacy of the work done here, but it does show a need for the 22 year old code to perhaps be updated.

Previously it was only Government organisations and well funded criminal groups that could hack the calls due to the requirement of equipment worth hundreds of thousands of £. 

It is suggested just $30,000 worth of equipment is all that is needed now.

For a technology sector where the products are changing so quickly why is it that the GSMA has not made it necessary to re-invent and make the code more secure?!

You can read more over at the BBC news page.