Attended transfer not working since v20 update

[matthewf]

Since the upgrade to v20, our phones only now allow for blind transfer and not attended transfer.

I found this ticket and tried to follow https://www.3cx.com/community/threads/attended-transfer-not-working-as-expected.127848/

I wasn't sure how to export my SIP trunks, would appreciate some advise.

Cheers