Hi guys ! We have a customer with 3CX Phone System v12 who has some workstations running Ubuntu. I've tested some software based phone clients, but no one works as I expect... Most of them work almost fine when they are in the local network, but no one works when the laptops are outside the LAN. The customer has CISCO network equipment and remote connections are made through IPSec VPNs. The best result I've achieved with SFLphone , which is available in the Ubutu Software Center. It could register through the VPN, initiate call, but no audio When the laptop is in local LAN audio is fine, but transfer and hold doesn't work .... If anyone has more experience with softphones in Ubuntu and/or Linux at all, please help !! Thanks !!!