It is important to note that NeuTrafiX does billing of full calendar seconds, not the rounded call duration in milliseconds.
Call started at 13:01:00.001 (last three digits is ms) Call ended at 13:01:0.999
In NeuTrafiX the call will be billed 0 seconds but in other systems it may have billed as 1 second.
Call started 13:01:00.999 Call ended 13:01.01.001
In NeuTrafiX will be billed to 1 sec, in other system where they roundup ms duration it would be 0 seconds.