DIFF Subgroup
H04M 7/1245 Full Title
Arrangements for interconnection between switching centres > for working between exchanges having different types of switching equipment, e.g. power-driven and step by step or decimal and non-decimal
H04M 7/1245 Arrangements for interconnection between switching centres > for working between exchanges having different types of switching equipment, e.g. power-driven and step by step or decimal and non-decimal