Adding SIP Push to Asterisk/FreePBX with Flexisip and a Custom Linphone Build
Back in 2022, I wrote a post about using an EC20 module with Asterisk and FreePBX for SMS forwarding and VoIP. The setup could already route calls from the SIM card in the EC20 to a SIP client, but the post ended with one fairly serious usability issue: the SIP client on my phone had to stay running. Otherwise, incoming calls could not reach the client, and the caller would hear a busy tone. At the time, the only easy solution I found was Zoiper Push Proxy, which was not free. ...