Oh yes, we have 4 lines from IDSN. For example, line 1,2,3,4.
I press button on Dterm and it shows line 1 "DDD 1001" , line 2 "DDD 1002" , line 3 "DDD 1003", line 4 display nothing.
As my memory (Im not sure), before line 4 display "DDD 1004" or "DDD 1000") and I can call to line 4 at that time...