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Problems with setting up a Secure Call
by the called party because he/she hears a modem sound when picking
up the phone. Some providers may not pass data calls to certain other
providers at all.
Under certain circumstances, especially when roaming in GSM networks
that are not properly configured, the "never ending key setup" problem
may occur. The phenomenon is that the key setup phase takes longer
then 20 seconds and never comes to an end. The underlying technical
problem resides in the GSM network. Data calls are sometimes set up
but then fail to transport any data.
All of the above conditions may make it impossible to use the CryptoPhone
in one or both directions between two CryptoPhones. As a work-around
if you are roaming try switching providers. If secure calling only works
in one direction, you could use an unencrypted call to tell the other party
to call you using CryptoPhone. These problems are inherent to using the
CSD data call facility and apply to all encrypted telephony over GSM. For
customers in Europe, North Africa and Asia who experience such problems
we recommend our CryptoPhone 200T solution that uses the Thuraya
satellite system to provide affordable secure communication also in areas
that are outside GSM coverage or have no suitable GSM network setup
for data calls.
Sometimes a specific condition of the GSM network leads to an unstable
state of the GSM part of the CryptoPhone, which also might cause the
"never ending key setup"-problem or other undesired behaviour. This
condition can sometimes be fixed by soft-resetting the CryptoPhone.
