  The telephony over IP (ToIP) is becoming a new trend in technology widely
used nowadays in almost all business sectors. Its concepts rely on transiting
the telephone communications through the IP network. Today, this technology is
deployed increasingly what the cause of emergence of companies is offering this
service as Switzernet. For several highly demanded destinations, recently fake
vendors appeared in the market offering voice termination but providing only
false answer supervision. The answered signal is returned immediately and calls
are being charged without being connected. Different techniques are used to
keep the calling party on the line. One of these techniques is to play a record
of a ring back tone (while the call is already being charged). Another, more
sophisticated technique is to play a human voice randomly picked up from a set
of records containing contents similar to: hello, hello, I cannot hear you
Apart the fact that the fallaciously established calls are charged at rates of
real calls, such malicious routes seriously handicap the switching process. The
system does not detect a failure on signaling level and is unable to attempt
the call via backup routes, the call technically being already connected. Once
the call flow falls into such trap, the calls will continue being routed via
the fraudulent route until a manual intervention.
