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MultiVOIP User Guide  
Technical Configuration 
 
113
 
  
H.323 Call Signaling Parameter Definitions 
(cont’d)
 
Field Name 
Values 
Description 
H.323 Version 4 Parameters 
 
Parallel H.245 
(FS + Tun)
  
Values
: Y/N
 
Description:  
FS (Fast Start or Fast Connect) is 
a Q.931 feature of H.323v2 to hasten call 
setup as well as ‘pre-opening’ the media 
channel before the CONNECT message is 
sent.  This pre-opening is a requirement for 
certain billing activities.  Under Parallel 
H.245 FS + Tun, this Fast Connect feature can 
operate simultaneously with H.245 
Tunneling (see description above). 
Annex –E (AE)
  
Values
: Y/N
 
Description:  
Multiplexed UDP call signaling 
transport.  Annex E is helpful for high-
volume voip system endpoints.  Gateways 
with lesser volume can afford to use TCP to 
establish calls.  However, for larger volume 
endpoints, the call setup times and system 
resource usage under TCP can become 
problematic.  Annex E allows endpoints to 
perform call-signaling functions under the 
UDP protocol, which involves substantially 
streamlined overhead.  (This feature should 
not be used on the public Internet because of 
potential problems with security and 
bandwidth usage.)