Aastra 480i Bugfix - More from the Junction Networks Lab

If you have an Aastra 480i, you may have noticed the note in our Knowledge Base about a bug where the 480i stops sending or receiving audio on transfers across NATs to certain phones. With the currently available firmware, the 480i writes the Refer-To in the SIP REFER packet to the user@IPAddress, which works just fine on a LAN, because the IP address is always available. Once the Internet and a NAT is introduced, this fails, since the two phones are no longer on the same network. Certain phones from other vendors can compensate for the problem, but we found that Linksys and Grandstream phones do not. The Aastra 5xi series of phones do not have this problem.

We've been working with Aastra to get this bug resolved. (It must be said that they were very responsive once we reported it - the delay in testing it was entirely ours.) They've released a beta firmware update (1.4.3), which we tested. It resolves the problem nicely, so we'll be updating our Knowledge Base as soon as it becomes generally available, which should be in the next week or so.