If an internet connection is available, CallTiger will use that to send the initial request. If there is not at least 3G connection available, CallTiger will send the initial request using a text message (SMS). If the number linked to your account is a Belgian one, an SMS will be sent to a Belgian mobile number. If the number linked to your account is from a different country, an SMS will be sent to a UK mobile number. Once the call has been set up, the call itself is made over the mobile GSM network.