Hi, We have 3CX V10 connected to a Sangoma A101 ISDN PRI gateway. When an incoming call is received and transferred to another phone in the company, there is a delay of between 2 and 4 seconds where the staff member cannot hear the caller (the caller can hear the staff member fine during this time). After that the call can be continued normally. We are not using SIP trunks, it's all going over ISDN. Any ideas why this would happen?