PSTN Phone + PBX Connection

I have a FreePBX box that I am using with a PSTN line but I also need to use that same line for an analog phone outside of the PBX system. This same line also services a fax machine. I realize this is not the best way to use a PSTN line but it is what I have to work with at the moment.

I can explain the setup in detail if needed. I can make outgoing calls fine through the PBX and faxes can be made and received. I can also make an outgoing call on the analog phone but it seems to call “twice.” The first is the actual call that receives input and audio as expected. The other is an out of service call.

I was wondering if anyone needed to implement something similar and had this problem? If so how did you resolve it?

If you need more information please feel free to ask.