GSM is a digital system with built in A3/A5 algorithms. However, being a known standard which has been in the market for some time, these algorithms could be easily deciphered by most professional and hackers who have already developed special equipments targeted for such interception.
In addition, A3/A5 algorithms are only present for digital transmission over the air. In other words, at the infrastructure end, it will be deciphered and unprotected as the trunk line is used. At such, it is easily tapped by the operators and other eavesdroppers.
All mobile users basically are opened to interception threat on their: •- over the air conversations •- messaging & data transmissions
If you are someone who prefer to communicate in private, crypto phone is suitable for you. Typical users are mainly corporate executives, lawyers, accountant, bankers, private investigators and government officials.
Crypto phone is designed to offer highest level of security possible and still become affordable. Certain military levels of phones were designed to also protect against exotic threats such as eavesdroppers. Dallab Crypto phones are primarily designed for commercial market. The goal is to protect against eavesdroppers who listen to the call at any point while it travels the networks. However, this does not provide sufficient protection against national intelligence agencies that considers you a high-profile target.
No, upon making a call, the crypto phone will set up a secure connection between two phones. During this period, the phones agree on a very long and secure ‘session code’. At call ending, all parameters are wiped from memory; therefore, no one can reconstruct the code used.
It is advisable not to bring the defective crypto phone to any normal mobile phone repair centre. We recommend users to return to the manufacturer or the authorized agent to repair to prevent anyone from tampering with it.
Today with total cost USD1,000-1,500 by using “field-programmable gate array” or FPGA hardware device, you can decrypt a recorded GSM phone call or text message in about 1 hour.( source washingtonpost.com )
This approach of line interception occurs in todays' mobile world. One could easily clone a SIM card, by using a special design sim card programming tool and software. It means one can clone as many mobile sim card as he wants with the same mobile number which could have the capabilities of receiving all calls and messages as those of its original SIM card mobile user holder.
Today, it is widely use in Asia Market and the cheapest, easiest and fastest way.