Here is a working configuration for a Patton 4114 FXS running 5.4 where the ports are used as inside POTS extensions.

Overview of setup

Each of the 4 FXS lines connect to simple legacy POTS devices. Some of these are in hunt groups under sipXecs and some not. The only slightly tricky part of this configuration was getting each line to send different caller ID.

The first line registers on two userids (205 and 233), the others on only one.