Anyone dealing with Panasonic PBX & Mobile Softphone app? Troubles!

Panasonic offers an app to SIP communicate with PBX NS-500, however it’s very buggy.

This is a conceptual diagram of their infrastructure:


Basically the apps will require authentication to Panasonic servers each time being opened/used. The process might require seconds. Once authenticated, the mobile phone OS must wake the app, that in turn, must connect to the SIP server, remotely or locally.

The whole process might require 10 to 15 seconds to make the app ring. Congrats to Panasonic engineers to design such a failure. I wonder if white collars in Japan di ever realise what a mess is this app.

Now, to get things worst, 40% of the calls, in LAN, will fail.
No ring on the other end.
So we have disabled SIP-ALG and will see if this helps, but we think one of the causes might be the app opening connections on multiple Peplink Balance One WANs.

As one of the requirements is:

The Mobile Softphone can be connected to the PBX locally through a Wireless LAN connection or remotely over internet (through Wireless hotspot/access or Mobile Data networks).

In either configuration, the Mobile Softphone client must use the same network connection to reach the Panasonic Authentication Server (cannot use Wireless for SIP to PBX and Mobile Data for internet access to authentication server).

I wonder if this could be the culprit as the sentence is a bit confusing, or if any other setting might interfere with communications.

In our scenario, we have setup a VLAN for PBX, and InterVLAN routing is enabled from any other LAN/VLAN, when destination is PBX VLAN. Port mapping and open ports are set to allow incoming communications from the Internet

Maybe @MartinLangmaid & @Don_Ferrario may throw a few cents on this topic?

Here’s a link the complete PPT presentation