PABX stands for Private Automatic Branch Exchange. A PABX is the same as a PBX although it precludes manual switching. Modern PBXs are all PABXs although the difference in the name has become less relevant. There are many PABX manufacturers, and service providers will tend to focus on one or two to offer configuration advice for. Nextiva’s trunking service is PBX-agnostic, we provide service to any SIP-based PABX.