If you wish to switch to VoIP, seriously consider native VoIP phone instead of classic analog phone connected thru PSTN<->SIP adapter.
I would like to confirm it can be configured using https in the browser.
It can be configured by http in the browser. Assuming the IP address has been assigned to SPA112 by either DHCP or manually thru IVR. And assuming you have retail unit, not the RC one. RC unit is the one customized for particular VoIP provider. You will not have access to configuration of such unit.
