The Grandstream Handytone 386 provides the clear audio quality that you would expect from Voice over IP. The adapter has 3 telephone jacks on it, 2 for Lines 1 and 2 and the final port is a PSTN fallback port that bridges Line 1 to a POTs line during the loss of power. It is also worth noting that incoming POTs line calls get bridged to Line 1 as well allowing for a migration from the POTs line and using a VoIP account for cost effective dialing.

Another advantage over the Linksys ATAs is T38 support. The Grandstream provides T38 udp capabilities. The device tested well sending a fax to a CallWeaver (formerly Openpbx.org) server. Receiving didn't work well, which proved to be a fault of CallWeaver and not the Grandstream. Two way faxing is successful using a T38 provider such as Gafachi.

The main problem we had with the device was with NAT. The ATA supports STUN for NAT traversal. However the problem we experienced was when STUN was enabled and both the ATA and call server were on the same LAN segment. The ATA incorrectly placed the discovered public IP into the SIP headers instead of detecting that the ATA was on the same LAN as the server. Disabling STUN fixed this issue however it prevents the ATA from being unplugged and easily plugged into another network with minimal changes. The adapter also supports XML configuration files via TFTP or HTTP. However, we would like to see HTTPS support added for an extra layer of security.

Overall, if we needed an IP analog telephone adapter, this Grandstream Handytone 386 ranks number one on our list. All it needs is good T38 support from software vendors and a quick fix for STUN.