Section 9 - Hacking the FOVC

One of the more usefull parts of the Motorola Bible

Note: This is NOT my hack. Thanks to Patrk@delphi.com for this addition.

HACKING THE FOVC


Problem: When listening to something interesting (a conversation), just when that sexy sounding horny broad begins to give her phone number to some lucky guy, HANDOFF!!! then static... DAMN!

Trick: Hack the FOVC.

    a quick definition:  FOVC  = FOward Voice Channel
			 FOCC  = FOward Control Channel
			 REVC  = REverse Voice Channel
			 RECC  = REverse Control Channel
 

As the phone travels through cells, the FOVC is where the tower tells the phone to adjust power levels for the current cell or to change to a new channel for use in the new cell. This info can be hacked apart. So. When you've found a good conversation, don't be lazy! Enter 40#! This makes the phone listen for commands on the voice channel (embedded in the audio portion- you can hear it as a "bump" sound). It will just sit there and the display will read '40' , but the conversation will still be audible. Now when the phone receives a FOVC command (a 40 bit sequence) data will flow across the display, in hex format, and stop. Listen to the phone, if the conversation is still there, then the [command\ was only to adjust power levels. If the conversation is gone, then its a handoff. If you only got a power adjustment command just press # or clr, which ever gets you back to the ' prompt. Enter 40# and keep listening. You can also use the # key to cancel the 40# command, if you want to change channels or something.

If it was a handoff, its time for some quick math. You have to convert some of the numbers to binary, and then to decimal. I don't know how many characters your phone's display will show. Mine only shows the last seven of the ten hex digits. Count left from the end 6 digits. Write down that digit and the next two on a piece of paper, i.e.:

    ???j16djjj    j=junk numbers  (hex numbers range from 0-9,a-f)
    / \
    these are lost due to scrolling
 
       write down  16d then convert it to a binary string:
 
       1 = 0001
       6 = 0110
       d = 1101    (d=13)
 
       now you have a binary string like this:  000101101101
       throw away the first 2 bits and get:       0101101101
       convert this to decimal and get:                  365
 

365 is the new channel the conversation has moved to! Enter 110365# and voila! You too, can hear the horny babe's phone number!

Don't forget to enter 40# again, as the call may be moving quickly through cells ( small cells or freeway driving ) or the call can get bounced around by the tower for cell traffic purposes.
Here's one more example of the hex to binary to decimal conversion.

	???j5aejjj
 
	5  =  0101
	a  =  1010
	e  =  1110
 
	full string        = 010110101110
	truncate 2 msb     =   0110101110
	convert to decimal =          430

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