Upgraded from 16.2.14 to 188.8.131.52 on Fedora 13, with aastra 9133i and 57i.
On 9133i and 57i:
## works for a blind transfer.
All this worked on 184.108.40.206.
Nothing useful on cli, verbose 3, DEBUG. Here extension 169 answers an
outside call, and tries to transfer it to 145 using the Xfer button: