Telephone Wiring Stuff

This section contains information on telephone cabling for ISDN.

U Interface

North American Demarcation point. A 2 -wire interface (single pair) that is usually but not universally provisioned using an RJ45 connector (more correctly an 8 position modular connector). ISDN wiring uses LAN based pair numbering NOT telephony pair numbering.

Pin No.	strand color	Name
1	white and orange	N/C
2	orange	N/C
3	white and green	N/C
4	blue	U Interface
5	white and blue	U interface
6	green	N/C
7	white and brown	Optional -48 VDC
8	brown	Optional -48 VDC (return)

Power for telephones is optional and if present is supplied on pins 7 & 8.

S/T Interface

Europe's demarcation point and via an NT1 for North American users. a 4 wire interface universally provisioned using an RJ45 (8 position modular connector). ISDN wiring uses LAN based pair numbering NOT telephony pair numbering.

Pin No.	strand color	Name
1	white and orange	N/C
2	orange	N/C
3	white and green	RX+
4	blue	Tx+
5	white and blue	TX-
6	green	RX-
7	white and brown	Optional -48 VDC
8	brown	Optional -48 VDC (return)

RJ45 Connector Pin Numbering

RJ45 Male Connector

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