I managed to capture the OnSIP account SIP regstration network fraffic from a softphone app - CounterPath Bria.
I also entered the supposedly correct data for such OnSIP account into OBI-200, and managed to capture the network traffic therefrom.
When comparing these two traffic, I found they are vastly different from each other, both in format and in content.
Yet CounterPath Bria can register, and OBI-200 can't.
Very strange!
I suppose the OnSIP server expects one and only one standard-format incoming SIP-regression request data. Is CounterPath Bria not following standard SIP registration protocol, or is OBI-200 not following standard SIP registration protocol?
I tried to reverse-engineer Bria's network traffic, extract some data from it, and enter them into the seemingly right fields in OBI-200. But OBI-200 still can't register.
This OnSIP company is really a strange company, behaving very odd, comparing to other major free SIP-account providers who all adhere to standard SIP protocol.