Hi there. I don`t know if 4400 supports SIP, however if you implement somethying like this, you should take in mind that in case of incompatibility, you could use a sipura 3000 or AVM fritz box ata as an incoming analogue trunk to the PBX for this system, in order to support SIP. several ATA`s could be used to increase simultaneous active calls...
I also think that the cost of these units is low! |