One Stage Dialing; Fax Support - Grandstream Networks HT503 User Manual

forwarded to another VoIP number previously configured in the field:"Forward to VoIP". This parameter can
also be found under BASIC SETTINGS configuration page.

One Stage Dialing

This feature is applicable for VoIP to PSTN calls. Any VoIP extension may dial directly to a local PSTN
number if the one-stage dialing feature is activated. This feature is configured under the FXO Configuration
page and requires SIP Server configuration and support. The special dial plan feature must be activated
in the SIP Server. An outbound call will be sent directly to the assigned FXO port account, where there
the HT503 will initiate a call to the local CO. The RequestURI header in the INVITE message contains the
phone number used to initiate the call to the local CO.

FAX Support

HT503 supports FAX in two modes: 1) T.38 (Fax over IP) and 2) fax pass through. T.38 is the preferred
method because it is more reliable and works well in most network conditions. If the service provider
supports T.38, please use this method by selecting Fax mode to be T.38 (default). If the service provider
does not support T.38, pass-through mode may be used. To send or receive faxes in fax pass through mode,
users must select all the Preferred Codecs to be PCMU/PCMA (G.711-µ/a).
P a g e | 30
HT503 User Manual