Siemens SINAUT ST7 System Manual page 223

Installing and putting a SINAUT modem into operation
5.6 LTOP line transformer with overvoltage protection
Attachment to a 2-wire end point
2-wire end point over an LTOP 1 2-wire end point over an LTOP2
1
2
Attachment with a 4-wire end point or 2 x 2-wire end point
4-wire end point over an LTOP2 2 x 2-wire end point over an LTOP2
2 1
2 1
Station control system
223
System Manual, 07/2009, C79000-G8976-C178-07