Updating firmware on a gxp2020
Currently, changing the transport from UDP to TCP seems to resolve these issues.
This has been tested against firmware 2.6.0 all model Aastra phones.
This lets the Free SWITCH server return SIP traffic on the same port your phone sent SIP traffic out on.
Enabling STUN support may also help on the newer firmwares.
A lot of users have complained about presence not working properly with Aastra phones.
This grid shows the tested features of various devices. This information is being merged into a feature grid, see Interop List Scratchpad Please make sure you put the following entries 2n Voiceblue Lite Config Later than 2.3.1, Aastra Phones (55i, 57i) are working very well behind NAT, tested with rport enabled, very reliable, and also connecting with proxy/registrar ports other than 5060.
These have been tested with firmwares later than 2.3.1.