Android as Dialup/FAX Modem

Question

With some older cell phones, you can connect them to a computer and use them as a Dialup/FAX modem (to connect to a dialup ISP for example). I have been trying to find out if this possible with Android, but all my searches end up with people looking to share their phones Internet connection with their PC. This is NOT what I'm looking to do. I'm wanting to use Hyper-terminal to have my phone place a call to a PBX, so I can make changes to the PBX remotely.

Flush

Answer 1

As I already expressed here, your stock Android phone cannot be used as an AT modem. - There isn't even a serial connection built in.

Question: How is the PBX controlled anyway? Does it implement an "analog" CSD modem, like FAX machines use(d) to?
In that case, you'd be completely out of luck since GSM/UMTS/... data transfer works quite differently.

Footage

It is a straight analog modem like, like a FAX modem. For example, if I had a 56k modem in my PC and land line phone, I could use Hyper-Terminal to place a call to the PBX and administer it through Hyper-Terminal – Flush

According to different sources I found, apparently it is possible to connect a GSM device to an analog modem via a circuit switched connection. It seems that this is not supported on most devices and requires the device to support some kind of serial connection and, more importantly, the AT command set ("ATD ..."). - No way to do that on a stock Android device. – Footage

Can you share the links to those sources please? – Flush

Sorry, was just browsing the net. Try searching for "GSM" and "fax" or "GSM" and "analog modem". – Footage

Smartphones have two computers in one. The computer that runs andriod / applications and a completely separate computer that runs baseband interface to the cellular network. Baseband processor provides a serial/AT command interface to the smartphone and you can often access it by configuring USB cable as a serial modem. If/how this can easily be done varies by manufacturer usually by entering a magic dial code. Once it is switched a serial/modem device should appear on the USB port. – Taunt

Answer 2

It can not be that difficult to set up if you use a SIP account to fax. I have a PBX in a Flash installed at home. There I use Hylafax to communicate over SIP to my SIP provider. I guess you could use Google Voice for this?

Muricate

Answer 3

It seems to me that if an app can be written to remain active during a call and send an audible tone of a specific frequency for a specific duration then the code for a terminal could be translated over (if you can get the source).

No need for bluetooth or wifi or usb.

I came here looking for an app to let me hold my phone up to a phone receiver to receive a fax or connect my headset outlet into an RJ12 phone outlet.

If I find anything useful I will try to remember to come back and post it here.

Maurer

Thanks! I will send you a message if I ever find anything. – Flush

Answer 4

It is possible using bluetooth. Most android phones (if not all) have a bluetooth dial-up service, suitable for using with e.g. Microsoft Windows Fax tool. I could not find a way to use it via USB, though.

Chemo

Answer 5

Interesting question, you're trying to call through the phone to dial up? According to this forum, there seems to be few documented ways to control the phone other than getting phone's state and signal strength, and other info. You could browse the source to see how Android dialer app itself works, but if you can send tones through the phone system you would still need to implement the protocol over usb or bluetooth, that would probably require some methods that aren't in the api, but perhaps may be available in the NDK?

Kerk

Answer 6

The bit rate for standard GSM calls is about 13 kbits / second. Conversion of an analog modem signal to a digital signal will entail some loss of resolution. So even if you did this you probably would not be able to transmit anything faster than like a 1200 baud modem signal.

Jann

Actually, you would. GSM supports so called "data calls" (CSD) in which fax data are not transferred as sound. I have successfully used it to send faxes in the past, but I had to call my network operator to have this activated. – Proton

Answer 7

locate usb driver for your phone,install on computer, set up new " dial up connection" on verizon phone # to dial is #777 user is your phone# password is vzw . i live where there is no options for internet except Sat and MiFi and at 100-250 / mo not a valid option. so i chose this method. the hardest part i have found is locating drivers (modem) for the phones hope it helps

Alveraalverez

This is not what I'm looking for. I don't want to share the Internet connection. I want to use the phone to dial into and configure a remote PBX. – Flush