Need help for asterisk1.4 voice quality

i’ve setup two server which runing Asteriks1.4 on Fedora5.
as structure is cisco as5300 A ->SeverA --> serverB -> as5300 B
the codec is G729,all the Asteriks server passthrough the calls UDP packets.

so when Cisco A to call Cisco B through the Asterisk system,the voice quality is not stable. at first 5 seconds,CiscoB could not hear CiscoA at all,and the following B can hear
anybody can give some advice thanks .

More informtion please. I’ll assume that Cisco A and Server A are on one LAN an Cisco B and Server B are on another LAN. Describe the IP network between Server A and Server B. If the Internet is between Server A and Server B, then that is your problem! There is no QoS assurance on the Internet.

all your assumed were real.
the internet between ServerA and Server B are perfectly good.
i don’t think the bad quality reasn is internet bad quality.
just because if servers run asterisk 1.2.13 ,all the quality is OK.

What are you trying to accomplish??? What is the goal and why the 2 as5300’s… These interface/TDM to another pbx or PSTN??? What about clocking on these 5300s? Where from and what stratum?

Need a better pic of what the end game looks like…