Hi All, Im going to try to explain this as simply as I can. We have 6 sites that have sip phones and want to implement 1 master 3CX server in a datacenter. Each site is VPN'ed to the Datacenter using either point to point private links or VPN over the internet. Im trying to find out information on what would be required if each site has a requirement to have a fallback/failover option in case the SIP phones cannot register to the 3CX master server. Now the fallback should not be a PBX but somekind of media gatewaY (1 installed at each site) with a few POTS lines as a fallback option, so that at least each user would be able to call PSTN or 911, but not necessarily be able to call within the office using 4 digit. I have been approached by SIP carrier that offer this as a failover scenario but trying to find out how this is could be done with 3CX, but i don't want a 3CX at each site, because I dont want to have to configure a users extension at the Datacenter and also at his local site. I hope this is clear and if not, please ask and I will try to further describe.