RJ9 RJ10 Telephone handset
RJ11 - 1 or 2 phone lines outlet
RJ14 - 2 telephone lines
RJ25 - 3 telephone lines
RJ45 Ethernet

Telephone:

pin	RJ25	RJ14	RJ11	Pair	T/R	±	Color	Old
1	X			3	T	+	white/green	orange
2	X	X		2	T	+	white/orange	black
3	X	X	X	1	R	-	blue/white	red
4	X	X	X	1	T	+	white/blue	green
5	X	X		2	R	-	orange/white	yellow
6	X			3	R	-	green/white	blue

T - Tip - ground
R - Ring - 48 volts
Ringing voltage is usually 88-110Vac, 20 Hz superimposed on -48Vdc.
Source: RJ11, RJ14, RJ25 - Wikipedia

Data - Ethernet

Standard	Required Pairs	10M	100M	1000M	Notes
10base-T	2 (1/2 and 3/6)	yes	yes	no	100m support only if no cat 3/4 in run
100base-TX	2 (1/2 and 3/6)	yes	yes	no	100m support only if no cat 3/4 in run
100base-T4	4 (1/2, 3/6, 4/5 and 7/8)	yes	yes	yes
1000base-T	4 (1/2, 3/6, 4/5 and 7/8)	yes	yes	yes	Functionally identical to 100base-T4

Source: Tech Info - LAN Wiring and Pinouts

Ethernet Wiring 8 Position 8 Contact (8P8C)
 (often incorrectly referred to as RJ45)
10Base-T and 100Base-TX
TIA/EIA  T-568B  - Most Common
pin color   function
1   wh/or   TxData +
2   or      TxData -
3   wh/grn  RecvData+
4   blu    
5   wh/blu 
6   grn     RecvData-
7   wh/brn 
8   brn     


TIA/EIA T568A (Transmit and receive colors reversed)
Based on original AT&T USOC (Universal Service Order Codes) standard
pin
1  TD+  white/green
2  TD-  green
3  RD+  white/orange
4       blue
5       white/blue
6  RD-  orange
7       white/brown
8       brown


A cable wired with 568A at one end and 568B at the other is a crossover cable

Links:
RJ - 45 wiring standard
Tech Info - LAN Wiring and Pinouts
568A v 568B