Grandstream ht-503 User Manual

 

Grandstream Networks, Inc. 

Page 15 of 37  

 

Any VOIP call may be forwarded to a specified PSTN number. FXO port should be registered with some 
preconfigured number (for example 1111). Any VoIP extension can dial this FXO account number and will 
be automatically forwarded to preconfigured PSTN extension. 
 
For example, if the end-user has configured a cell phone number in the field “Forward to PSTN” under 
BASIC SETTINGS configuration page, all calls will be forwarded to the cell phone number after 4 rings.  
 

By default, each incoming PSTN call is received over the FXS port.  The end-user may forward such a 
call to any preconfigured VoIP extension, in case the call is not answered in a certain number of rings. 
The Default value of the parameter “Number of Rings” is 4. This parameter located under “FXO Port” 
configuration page. If during 4 rings, the incoming from the PSTN call is not answered, the call will be 
forwarded to another VoIP number previously configured in the field:”Forward to VoIP”.  This parameter 
can also be found under BASIC SETTINGS configuration page. 
 

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. 
 

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).