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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