I've found out the following functions on an NEC TR5E1320-9A cell phone.

Before trying any of these functions you must first get it into test mode.
 This is done by taking it to bits and locating two metal contacts underneath
the battery section.  The one to the right  will have "TEST" printed by it,
the one to the left will have "AGING" (not sure what this is for).  The TEST
contact needs to be grounded, the easiest way is to solder some wire from
TEST to the metal shielding.  Once this is done you can then re-assemble the
phone.

Power up the phone and press:

RCL # 

The display should now say TEST MODE

Then press 01
The display should be filled with blocks.

You can now enter the commands that follow.

Please note that a ? by a function means that it does something, but I don't
know what.  And a X means that it comes up with ERROR, presumably there is
not a function associated with  it.

Press RCL # before all numbers:

01	Enters test mode
02	Takes out of test mode
03	Displays two rows of digits (six on top, 10 on bottom)  Appear to be
signal strength
04	?
05	x
06	Turns sound off
07	?
08	?
09	Allows direct channel entry of 4 digits # to end
10	Can enter a number from 0 to 7 # to end ( don't know what this does)
11	Sound off
12	Sound on (Should hear data from speaker)
13	?
14	?
15	Causes phone to reset, similar to power off then on.
16	?
17	?
18	?
19	?
20	x
21	x
22	x
23	Displays version number
24	x
25	x
26	x
27	x
28	x
29	x
30	x
31	x
32	Enter a digit between 0 and 3 # to end, don't know what this is
33	?
34	X
35	Plays a high tone
36	Turns high off
37	Plays low tone
37	Turns low off
39	?
40	x
41	x
42	Tests touch tone on keypad
43	Touch tone off
44	Ring tester
45	Engaged tone
46	No such number tone
47	x
48	Turns off ring etc
49	?
50	Signal strength
51	x
52	x
53	x
54	x
55	?
56	x
57	?
58	x
60	Digits 0 to 3 
	0	output to ear piece
	1	output from ear piece and speaker.  Volume with up,down arrows on handset.
	2	same as above, but must be different somehow.
	2	output to ear piece, with volume control, very quiet

61	can enter digits 0 and 1, don't know use.
62	?
63	x
64	x
66	x
67	x
68	x
69	Audio Scanning.  This is the cool bit where you can listen in on cellular
conversations.  You can enter 4 digits, there are two sets of channels 0000
to 600, and 1329 to2047.  When you have entered the channel you want to start
scanning from press #,  the phone will then start scanning from that channel.
 Say you started from 1400, the display will look like this:

0400-XXX 

(The XXX referring  to the signal strength).  When a strong channel is
received you can press * to stop scanning, and * again to resume.  I've found
the best channel to start from is 1400.  Although this might be just in my
area.

PLEASE NOTE that you must have the audio turned on (RCL # 12) to hear the
conversations.

70	x
71	Enters programming mode.  "Phone No."  should be displayed.  Following the
following # keypresses will give the following:

Phone No.
#	Lock Code
#	Home Area
#	Sys Select (1=A VODAPHONE, 2=B CELLNET)
#	System No.
#	Roam (1=Yes, 0=No)
#	Timer SW. (1=V Voice CH, 0=CR Charge RT)
#	Priority

If you want to change any, enter the required number and press #, when
finished press and hold CLR.

72	x
73	x
74	x
75	x
76	x
77	Not sure about this one.  Displays "T" then a 4 digit channel can be
entered, pressing # displays an "R" another 4 digits can be entered.  I
presume the "T" and "R" refer to Transmit and Receive, but I can only receive
in Audio mode. 

78 to 93 don't seem to do anything.

94	I think this is some sort of squelch, when enabled the signal to noise
ratio is increased.
95	Squelch off
96	x
97	x
98	x
99	x


Well there they are, took me ages to try them all.  Hope they are of some
use.  Could you please e-mail me if you know what the functions that I'm not
sure are for, and what the T and R on RCL # 77 are for.  If you think this
document is any use could you please put it on your web site.

Thanks...