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Full SIM access with Nexus 5 and Mercedes SAP v4?

Discussions about rSAP and general Bluetooth compatibility of the Mercedes-Benz Bluetooth SAP telephone module
Posts: 15
Joined: Fri Dec 13, 2013 10:44 pm

Full SIM access with Nexus 5 and Mercedes SAP v4?

Post by delicats » Tue Mar 04, 2014 5:32 pm


The Mercedes SAP v4 supports apparently parallel operation of a data modem connection through the USB port.

I want to connect a 3G Wifi router to the port in order to have an 'In car Hotspot' (and finally to reconnect the data connectivity of the phone in the car while the SIM credentials have been 'stolen' by the SAP module).

I am using a Nexus 5 with the latest Android version (4.4.2) and rSAP to connect with the SAP V4 module and this works fine. But the USB port seems not to react on the router being plugged. The router does have a nice feature and differentiates between the modem being 'unplugged' and being 'unknown'. So if I connect an unsupported modem it appears 'unknown' and I can install a config file manually. But when connecting it to the SAP V4 it just tells me 'Modem unplugged'.

In the display of the car radio (Audio 20) while using rSAP on the phone it tells me '2G Vodafone', which made me think that rSAP might be transferring only the GSM credetials (the SIM card in the phone is data enabled).

Is this a known limitation of rSAP with the Nexus 5 (I saw that obviously many phones have this problem) and is there any workaround except to use the SIM card slot of the SAP module and to forget about rSAP...which would be a pity as it is working really well for me so far...



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Re: Full SIM access with Nexus 5 and Mercedes SAP v4?

Post by admin » Wed Mar 05, 2014 8:36 am

I'm not sure if it makes a difference whether you connect via rSAP or put the SIM card directly into the SAP module. There is a lot of software between my app and the SIM card, maybe it changes something, maybe not. My app forwards everything unchanged on the Nexus 5.The software in the SAP module may as well behave differently when the card is accessed directly. At least it is possible to get the necessary data from the SIM card to create a 3G connection, as this works fine in VWs.

Is there any phone with which your configuration is confirmed to be working?

Posts: 15
Joined: Fri Dec 13, 2013 10:44 pm

Re: Full SIM access with Nexus 5 and Mercedes SAP v4?

Post by delicats » Wed Mar 05, 2014 9:30 pm


no, I have no experience with any other phone, but I tried today to use the local SIM slot and the result is the obviously no rSAP problem.

But I have a short question to the rSAP users that use the SAP V4 module with the Audio 20 (or any other except Comand Online): Does your operator show up as 2G or 3G connection in the Radio?

I currently have a bit the impression there might be a problem with the SAP V4 firmware.



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Joined: Fri Nov 29, 2013 11:57 pm

Re: Full SIM access with Nexus 5 and Mercedes SAP v4?

Post by Gagome » Mon Mar 17, 2014 10:04 pm

I have a SAP V4 module but with COMAND Online.
And I have seen both 2G and 3G connections.

The SAP V4 module even changed from 2G to 3G and vice-versa if there is 3G available or not.


I started the car in a closed area (parking space two floors below ground level) and the display showed 2G. This is to be expected because below the surface the phone would have a 2G only connection to the network anyway.
After I drove out of the parking area the display changed to 3G. Because now without walls the SIM card can get a UMTS (3G) connection.

Thies proved to me that the SAP V4 module tries to get the fastest connection (3G) but if I am in a location where only 2G is available than it switches back to 2G. It behaves just like a phone.

If you suspect a firwmare isse than update the firmware of the module. There is an update available.
I have updated mine. I didn't have any issues but after I found out there is such an update I installed it anyway.

Look at
Select there your car and you should come to a site from where you can download the latest firmware for SAP V4 Module and some instructions how to update.

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Joined: Mon Apr 06, 2015 5:36 pm

Re: Full SIM access with Nexus 5 and Mercedes SAP v4?

Post by sunnydude959 » Tue Apr 07, 2015 11:30 pm

I'll be interested to know if you guys got any further with this or got this working?

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