We need to connect the FXO ("Line") port of the SPA3102 to a circuit that has very low (or no) battery.
It appears that even if we set the Line-In-Use_Voltage parameter to 0, the SPA 3102 will not accept a one-stage outbound call to that line unless there is some minimal voltage present.
Is there any way to disable the SPA 3102's line-in-use detection so that it will connect an incoming SIP INVITE to the FXO port regardless of voltage present?