What applications should I use to make the Android device to forward calls from cell network to SIP or Skype and back?

One device ("Home") is expected to be left at home, serving as proxy; other device ("Travel") is just using data connection to connect to the first device, so it works like this:

  1. Someone is calling you using cell network.
  2. Home device receives the call and calls Travel using SIP.
  3. Travel device sees the incoming SIP call.
  4. You answer the call.
  5. Home device is proxying between SIP and cell network for you until you drop the call.

How to do it? How to workaround greedy cell providers?

1 Answer 1


There is an opensource application Sipdroid, which theoretically could be modified to do proxying. But, judging from the poor general Android SIP experience, I'd think it would be very unreliable solution.

Easier way to workaround greedy cell providers seems to set up an IP PBX on the home computer, or get a free account at freepbxes.org and get a cheap SIP-connected phone number to eventually route your calls thru while using your "Travel" device's SIP connection to terminate calls.

  • freepbxes.org fail to reply. Also I don't sure it will be available in my country (where state telecom monopolist protects itself with lawsuits against VoIP).
    – Vi0
    Dec 18, 2012 at 17:31
  • 1
    Oh, I see. I've got a few friends in Belarus, and telephony communications with them is the most difficult amongst all I'm calling nationally and internationally. Well, looks like Android won't do for this. Have a look here: stackoverflow.com/questions/4723453/… So your solution seems to be a computer-based PBX, e.g. Asterisk, with a cheap GSM voice-capable modem - that will be able to forward calls via SIP to your "Travel" handset. Dec 18, 2012 at 20:09
  • Can I use Android itself as voice-capable modem? For example, what will happen if I call with GSM and CSipSimple simultaneously (will it de-facto route the sound)?
    – Vi0
    Dec 18, 2012 at 20:23
  • I'm afraid CSipSimple (or any other user-level app for that matter) doesn't have access to GSM audio. Someone more knowledgeable should confirm if this is the case. Dec 19, 2012 at 19:39
  • CallRecorder applications does record calls, for example; and it even does not require the root access AFAIR. Also just recording from microphone should have some effect (poor quality although).
    – Vi0
    Dec 20, 2012 at 14:20

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