SIP-GSM Gateway for Android - repost


This is a repost!

I need an application that can send/receive calls through SIP (Can use any sip stack like sipdroid) and forward it to the GSM network. The application should then forward the audio and convert from SIP to GSM and vice versa.

The app should be able to run on cheap devices (+-100$).

I was thinking on a way to emulate a headset and set it as default, so just need to initiate a call on gsm network using core android functions and audio will be automatically forwarded. Maybe this is a solution.

Codecs: Minimum g711, desired g729.

Full description below. Please review and message me with considerations. If any requirements are unable to be met, please let me know before we make a deal.


o The goal of this project is to develop an Android application that can send calls through SIP and forward them to the GSM network AND receive calls from GSM and forward to SIP. The application should then forward the audio and convert from VoIP (RTP) to GSM and vice versa.

o The app should be able to run on cheap devices (+-100$).


o Deliveries

o The application working in APK format

o Full source code

o Simple manual for compiling and generating the application from source

o The project will be closed source and must be able to be sold on Google Play, so must NOT use an open licensing model that prohibits closed source code.


o Route call from SIP to GSM

o Route call from GSM to SIP

o Convert audio from/to SIP and GSM networks

o Can have 2 or more GSM chips (Only one call simultaneous but may choose the chip)

o Must be able to run on cheap devices like Samsung galaxy Y or Chinese devices like this ([url removed, login to view]).

o Able to run on Android 2.2 and up.

Application Configurations

o Enable or disable the app

o Enable to receive calls only on wifi or all networks

o Enable to route calls from GSM to SIP

o Choose a fixed number to send the call

o Enable to route calls from SIP to GSM

o Route the call to number on INVITE field or a custom field Or route the call to a fixed number defined by user

o Must run on background

o Must be very lightweight to run on small memory devices

o Configure SIP Accounts

o Create a mini dialplan to choose which chip to use based on techprefix

Sip Requirements

o Register on Sip Proxy/Gateway

o Receive call authenticated by IP, user/pass or no authentication.

o Make calls with or without authentication

o Forward DTMF digits using RFC2833 or inband

o Use codec G711 and GSM

o Be able to use codec G729

o Create a mini dialplan to choose which chip to use based on techprefix, per SIP Account

o Hability to register more than 1 SIP account (but receive just 1 simultaneous call)

o Be able to store a CSV with all calls made

Skills: Android, Software Architecture, VoIP

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Project ID: #4444050

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