Not so Secret Codes
Most of the codes below require somewhat rapid entry in order to work. If you can’t get one working, just try typing it in a bit faster.
Enable DUN: ##DIALUP
Programming Menu: Menu + 0 + 73887 + * (Security Code: 000000)
Enable Test Mode: Menu + 00 + ** + T E S T M O D E + *
Disable Test Mode: Menu + 00 + ** + T E S T O F F + *
Enter/Exit Text Mode: Menu + LeftOpt
Enter Operator Codes: Menu + 048263 + *
NAM Programming Menu: P H O N E (7 4 6 6 3) + # + Menu + Menu
Vocoder Menu: ## + VOCODER (8 6 2 6 3 3 7)

Operator Codes
Motorola phones support the use of operator codes to set miscellaneous options. I don’t have access (yet) to the v710 level 3 manuals, but many of the opcodes from previous models still work – I used this to boost the earpiece volume somewhat (although it’s still too quiet).

First, to enter the opcode screen, press Menu + 048263 + *. You’ll have to do this rather quickly. This will bring you to a box prompting you for an opcode. Before you can enter any codes, it will be necessary to suspend the phone. To do this, enter 54* and press OK. The display will go black and the phone will be suspended. Press the camera button on the outside of your phone to turn the backlight back on. You should see “SUCCESS” on the screen. Go back and then you can enter whatever opcodes you like. So far these are the ones I have that work – feel free to send more if you got them. About the only useful one is the audio level. I know there are more, but I can’t find documentation anywhere.

0*0*0 Select tone 0
0*0*1 Select tone 1
0*0*2 Select tone 2
0*0*3 Select tone 3
0*0*4 Select tone 4
0*0*5 Select tone 5
0*0*6 Select tone 6
0*0*7 Select tone 7
0*0*8 Select tone 8
0*0*9 Select tone 9
3*0*1 Enable vibrator
3*0*0 Disable vibrator
4*3*1 Enable speech coder full rate Audio loopback
4*3*0 Disable speech coder full rate
4*4*1 Enable speech coder enhanced full rate
4*4*0 Disable speech coder enhanced full rate
4*5*1 Enable speech coder half rate
4*5*0 Disable speech coder half rate
5*0*0 Set audio level 0
5*0*1 Set audio level 1
5*0*2 Set audio level 2
5*0*3 Set audio level 3
5*0*4 Set audio level 4
5*0*5 Set audio level 5
5*0*6 Set audio level 6
5*0*7 Set audio level 7
5*0*8 Set audio level 8
5*0*9 Set audio level 9
5*0*10 Set audio level 10
5*0*11 Set audio level 11
5*0*12 Set audio level 12
5*0*13 Set audio level 13
5*0*14 Set audio level 14
5*0*15 Set audio level 15
6*2*2*0*0 Set Audio Path. Int Mic, IntSpk, RX unmute, TX unmute
6*4*6*0*0 Set Audio Path. Boom Mic, Boom Spk, RX unmute, TX unmute
18*0 Initialize non-volatile memory (Master Reset)
18*1 Initialize Non-volatile memory (Master Clear)
55*2*001 Test Display. All pixels ON
55*2*000 Test Display. All pixels OFF
55*2*002 Test Display. Checkerboard pattern A
55*2*003 Test Display. Checkerboard pattern B
55*2*004 Test Display. Border pixels ON

This was taken from Nuclear Elephant