Grandstream Networks HT503 User Manual page 19

Provisioning NAT support traversal via STUN
Fax over IP T.38 compliant Group 3 Fax Relay up to 14.4kpbs and auto-switch to G.711 for
Fax Pass-through, Fax Data pump V.17, V.19, V.27ter, V.29 for T.38 fax relay
Security DIGEST authentication and encryption using MD5 and MD5-sess
Stylish and compact design; small universal power supply, ideal for travel
Physical Design
HT503 User Manual
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