On the Teltonika Configurator, GSM Predefined numbers can be set for a call to be initiated on selected event. These predefined numbers can consist of numbers only.
If it were possible to dial additional characters (specifically * #) , then the FMT100 would be able to contact me without having mobile credit. For example on Vodacom dialling the ussd number *140*0731231234# would instruct the network operator to send a free SMS on behalf of the caller (Teltonika device) to 0731231234, containing text similar to "Please call 0731231234". I would then know that my event has triggered, without using SMS or Airtime credit, and even if the sim card balance is 0.