voip 4AFXS อย่าลืม ตั้ง -service 1: HotLine service.

http://www.joyce.cz/files/technicka-podpora/prirucky/voip-zarizeni/wg3504_en-manual-sip-113.pdf
service Specify gateway service type. (0: Dial in service,   1: HotLine service.)