Juniper

You must disable the SIP ALG on the Netscreen router. Navigate to the 'Configuration' page and choose 'Advanced'. Then choose ALG and un-check the SIP check box.

The Juniper Netscreen NS-5XT (among others) has the ability to sense UDP floods. Sometimes VoIP traffic (which is UDP) can be detected as a UDP flood. To disable issue the following command: "unset zone untrust screen udp-flood"