SIP

Most AI voice demos stop at “the AI answers the phone.” In any real business, that is only the front door. The interesting part is what happens when the caller asks for Sales, Support, or a specific person — and the call needs to land on a real human. In this build I put a self-hosted FreeSWITCH PBX in front of a VAPI AI voice agent, with a Telnyx SIP trunk as the carrier. Calls land on FreeSWITCH first, get bridged out to VAPI for the AI conversation, and when the caller needs a human, VAPI issues a SIP REFER and FreeSWITCH rings the target extension — a softphone, a Yealink, or any registered SIP device. ...

Recently, I worked on a project where we needed to integrate a legacy Ericsson BP250 PBX with the Telekom Malaysia (TM MLS) SIP network. Since the BP250 is a TDM-based system, direct SIP connectivity is not possible. To bridge this gap, we designed a hybrid solution using a VoIP Gateway and a FreeSWITCH system. Architecture Overview The integration was built using the following components: Ericsson BP250 (Legacy PBX – E1 interface) VoIP Gateway (E1 ↔ SIP conversion) FreeSWITCH (SIP routing & header manipulation) Telekom Malaysia SIP Network (TM MLS) ...