Hi, I am getting stuck on read_frame and write_frame in my custom endpoint. Would someone shed some lights on how it works? My questions about read_frame, write_frame after reading mod_iax, mod_portaudio and mod_skyiax are: 1. Is it correct that I need to check a flag (for e.g TFLAG_HUP) of the private object at the beginning of the event to determine whether I should continue reading audio or just return. The flag TFLAG_HUP is set when a hangup or kill channel event is detected. 2. Read_frame is called on an interval (how frequently is the interval ? how do I determine that?) to read audio from my endpoint. 3. What is TFLAG_IO normally used for ? 4. What is the label "cng" is all about ? May I know what "cng" stands for and how it is used? 5. What if read_frame is called while my end point is not ready to send any audio yet? 6. What is the tech_pvt->cng_frame is used for? I notice that the *frame is set to tech_pvt->cng_frame if the label "cng" is reached. Thank you very much for even reading my questions. I tried to look for documents that explains clearly the above questions but so far no luck. Until now I still don't have a clear understanding about these 2 events yet. Best Regards Alex To