Hi, we have Aastra phones (models 4422,4425,5446). For PBX we are using 3CX (v.10 SP6). We know that this models are not official support to work with 3cx but they are working (inbound and outbound calls are working). The problem is with additional features like call transfer, conference, on hold call...). Telephones have final available firmware. Is there any posibility to make call transfer and aditional features to work via dial code or something else. Phones have function keys which can be configured via web interface but they only work with proprietary PBX (MX-ONE). The only way for call transfer to work is is via MyPhone. We need some solution to make that with physical phone. Please help. Best regards.