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Old September 28th, 2012, 04:34 PM
eaglevision993 eaglevision993 is offline
Join Date: March 24th, 2007
Location: Heidelberg
Posts: 151
eaglevision993 will become famous soon enough
Analog->Digital Phone Conversion! Done

as we know the older analog phones in the 98-2002 TownCars do no longer work in all areas in the US. Here in Germany they don't work at all anymore.

If you still want to have the stock look and convenience of an old school in car phone, you need to go digital. Thats what I did in the last 2 days and all went right thank God. Just wanted to give an overview in case anyone decides to go the same route.

This is not a job for the novice as it involves taking lots of stuff apart and lots of soldering! I did not have the original phone installed, but the premium Alpine stereo system.

Here is the overview.

First, I got a Motorola 2700 International car phone system.
This phone fits perfectly in the arm rest where the original handset would be.
The Transceiver is in the trunk and gets power from the subwoofer amp with a dedicated 5 amp fuse. The subwoofer circuit has a 30 amp fuse.

To make the phone mute the radio at incoming calls and use the car speaker system in hand free mode I had to hack somewhat in the audio harness behind the radio unit: The radio has 3 wires you will need: phone +, phone - and "transmit on" signal. The last one tells the radio when an incoming call comes so it rings through the speakers and mutes the current program. The wires are found in the FSM connector printout.

The mute wire from the phone sends a negative feed when it wants to use the car speaker system. That goes to the "phone transmit on" wire in the radio harness.

The phone + and - wires need to be connected to the phone speaker out BUT you have to use a high/low converter as the radio needs line level inputs and (at least my phone) drives a dedicated speaker under normal circumstances so it has its own amp inside.

Now all needed to complete the job is the microphone (comes with phone) installed and of course the antenna.

As for the antenna I went with a cell phone antenna that mounts behind the rear bumper and is invisible. No need to drill holes but you need to remove the bumper. Donīt have a model number for the antenna if used in the US as mine is a German one (Hirschman brand)which is actually used on older Mercedes S Class vehicles.

This is the antenna I used:

The system works flawlessly by now: Incoming calls mute the radio, the display shows "PHONE", speaker rings and hands free operation is also through the car speakers.

The only "original" features that donīt work is speed dial via the radio preset buttons and voice dial.

Some may ask WHYYYYYY go through all this trouble in todays smartphone world...well, I just like the look of a good old style car phone with its non-wireless handset and all...No internet, no email and all, just a phone, thats it. Fits the style of these cars.

I got a second SIM card with no extra charges to use in this phone so basically free aside from the costs for the phone of course....

If you have further questions or want pics let me know.

Best regards
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