Most common schematic of m-bus and c-bus interface cable. Suitable for most Nokia (M-Bus) and Bosch 508, 509, 607, 608, 718, 738 (C-BUS) cell phones cable connector
This simplified M-Bus scheme should be used with most Nokia cell phones (i.e. Nokia 8210, 8850)
In some cases (for Bosh cell phones?, Nokia 3210) more complicated scheme should be used
External power usually not needed, but may be used