Hi We have implemented 3CX for a customer who is all of a sudden having audio issues. The caller can't hear the speaker but work the other way round. If a call comes in and works fine, when transferred we have same issues. On a T49 which is non supported but works fine as SIP extension, all of a sudden (along with other issues), the call ring will drop after 2 rings. Also issues with transfer. Setup: 3CX server running on Windows server 2012 R2 which is a virtual server hosted with OVH. The phones are T48Gs and T27Ps. We also have 2xT49G, 3 x Algo paging adapters and 1 x 2N Helios IP force door entry system. Things were all working fine till last Friday but since we are having all kinds of audio issues. We installed 3CX SBC controller on the data server in the office where the phones are. The supported phones are configured using the Direct-Remote STUN method of provisioning and unsupported devices configured using SBC. Remember all phones and devices are on the same LAN in the office and 3CX server is remote. Issue is not related to firewall because firewall test passes fine and also the issues we are having are since last Friday, before that the setup worked fine for 2 weeks. 3CX support is totally out of clue what to do and how to fix it. I am asking help of members here if they can give me a solution/suggestion. Here is what I am thinking might be possible solutions. 1. Configure all phones through SBC controller, even the supported ones. 2. Move the 3CX server from remote server to a computer that is on the same LAN as the phones are. Then reconfigure all phones to connect on the LAN and the only traffic that goes on the internet is the SIP trunk. We have to come up with a solution quickly so any help/comment/suggestion would be great.