My scenario is as follows: my users subscribed to a sip trunk provider each having their own sip account and I want them to connect as such: their browser to JSSIP to to Freeswitch then to the sip trunk end point when making.

Given that freeswitch have the public gateway concept, can I dynamically change the gateway username and password to the ones provided by the user?

Or would there be an alternative solution? 

Regards,

Steve