We also have a network of PBX's tied together here in the US but using AREDN Mesh connectivity. Phone numbers are a flat 4-digits for local calling. For wide area calls, the person's (or service) 3-digit area code is prepended to the 4-digit local number. There are around 40 pbx's scattered around the world on this network. There is a White Pages directory to determine a person's (or service) phone number.

It would be interesting to try to connect the two systems together.

Of course it is always tricky to interconnect two systems that have a different and potentially conflicting numbering plan.

I actually like the numbering plan they use here. You number is not tied to the PBX you have registered on, but it roams with you wherever you connect. So when the local situation changes (someone stops providing the service or some more nearby PBX appears where you have better connectivity or better services) you can just port your existing number without problem.

And no directory is required, I can just dial numbers on the keypad knowing only the callsign. For you it would be 62206142

It would have been even better when they had thought of having some unique prefix that makes it recognizable as a HAM number and not a POTS phone number, and that avoids collisions with other numbering plans.

Rob