Need advice on cellphone hookup in A4

[Byas U Nambisan <Byas_U_Nambisan@ccm.fm.intel.com>]

Dan,
I would like to hook my Ericsson cellphone into the A4 jack (if 
possible).  I've seen postings from you on hardwiring your valentine and 
cellphone to the car and would like your advice/inputs. My plan is as 
follows:

Assumptions:
1. The A4 jack is of the std telephone connector type (WJ11?) with four 
wires.  The green is +ive and red is ground.  That would leave the other 
two for speaker and microphone.  

2. The Auto mute is a function of the Delta system such that it mutes 
when it senses a activity on the microphone/speaker connections.  

3. The Delta system provides the necessary amplification.  Impedance ??

Plan:
I have a speaker/mic connection for my cell.  I was planning to splice 
the audio and power connections to the telephone connector and plug it 
into the car.  If the above assumptions are correct, I would still need 
to figure out the connections on the adaptor:

White:    Mic? or Speaker? 
Green:    +12V
Black:    Mic? or Speaker?
Red:      Ground

Would this work?  Would I be seriously damaging the Delta system if I 
tried?  If anyone else on the list has any tips/info please feel free to 
send them directly to me.  I will post a summary of the responses/result 
if there is general interest.

Thanks,
Byas