I doubt it

PSTN line is only for FXO port, meaning that you have to use real PSTN (either inbound or outbound) in order to use the SIP configured in PSTN line tab. There no such thing called VOIP-TO-VOIP in SPA3102. As for VOIP-TO-PSTN, you need to call in with the SIP configured in PSTN line and then get forwarded out through PSTN.