Hi Nicky,
It works fine. However, we only using the analog lines link up them together. Actually, we want to use Universal SIP/H.323 Signal Converter to link up all the sites. Since, it is so costly that we give up.
http://www.welltech.com/product_e_2e.htm
I will send our simple diagram for your reference via email.
We also study/know how to setup analog DID (wink-start, immediate-start and delay dial service) for our 3CX BOX
Regards,
5Q