and never do callout service. you have to use other callout service, such sipGate.com or voipdiscount, but there is a problem of "FUP Exceed" if using voipdiscount directly at SS. Read 精華區 first please.
your callout at SS can be SS>>GV>>SG>>out or SS>>GV>>voxalot>>VOIPdiscount>>out.
your callout at SS can be SS>>GV>>SG>>out or SS>>GV>>voxalot>>VOIPdiscount>>out.