IP to IP faxing, both the sender and receiver need to be ip2ph members and have their fax machines attached to IP analog telephone adapters (ATAs).

One other important factor when faxing over VoIP is the quality and speed of your Internet connection. Since fax data cannot be compressed, the G711u/a CODEC must be used. This codec requires a minumum of 64Kb/s in both directions to be reliable, but we recommend more than 90Kb/s.