We can make use of the SIP trunk connection to connect mulitpule IPPBX togehter as an "ONE" communcation system. IT IS YOUR OWN "ONE" communcation system and which can intregate difference countrys PSTN Network by your own Dial Plan Setting.
It is the power of the IPPBX.
For more information:
Please contact our Solution Consultant at (852) 3900 1988