Can Huawei MDU equipment (such as MA5616) be used for internal exchange?

Hello, friend!

This function cannot be implemented only on the MDU. You need to register the phone number of each fixed-line phone with the PBX, and set the PBX to intercommunicate with each other. 

 Here, I will explain the concept and functions of the PBX.

- The PBX has two roles. One is a switching layer device on the private network and is responsible for address the location and services of voice users. Private network users can access the IMS network or PSTN network through SIP trunks.

- The access gateway (AG) is the media access gateway. Compared with the PBX, the AG is the model in which the POTS of the PBX registers with the IMS through the SIP trunk. The PBX registers with the IMS through the SIP trunk and the AG registers with the POTS through the user number of the POTS. The services of the PBX are basically the same. The PBX, however, implements all services of the PBX.

- SIP-based AG is called SIP AG.

- The AG based on the H.248 protocol is called H248AG.

Thanks!