using a Cisco 878 with PAT I got following issue:
This is the situation: There is a location with a few IP-phones, which register to the Central Office via SIP 5060. After that they establish RTP sessions to the Central office. The C878 got one official IP adress, the LAN got a private range (192.168.200.x).
After a few minutes there exist multiple duplicate UDP Nat translations, so communication of the involved phones fail:
#sh ip nat trans
udp 18.104.22.168:5004 192.168.200.46:5004 22.214.171.124:10000 126.96.36.199:10000
udp 188.8.131.52:5004 192.168.200.46:5004 184.108.40.206:10056 220.127.116.11:10056
udp 18.104.22.168:5005 192.168.200.46:5005 22.214.171.124:10001 126.96.36.199:10001
udp 188.8.131.52:5005 192.168.200.46:5005 184.108.40.206:10057 220.127.116.11:10057
ip nat inside source list NatToExternal interface Dialer1 overload
ip access-list extended NatToExternal
permit ip 192.168.200.0 0.0.0.255 any
IOS is: c870-advipservicesk9-mz.124-15.T8.bin
How can I get around these duplicate NAT ?
Thanks in Advance,