To ensure proper operation, your firewall device on the connection your handsets are using to reach your PBX as a Service must meet the following requirements...
1. We recommend that you use a firewall device on our recommended list....
Recommended Modems & Routers
2. You must ensure that the device is not listed as incompatible....
Known Incompatible Modems and routers
3. If you are running strict ACL's, your firewall configuration should allow the required IP addresses and Ports...
SIP Server Addresses
4. We recommend the use of a Private IP connection where possible for optimal voice quality and service reliability. Contact our team to learn more.