Using FreePBX and regular phones at the same time

The Setup:

I am currently using FreePBX and a few “regular phones” at the same time. The “regular phones” are not integrated into the FreePBX system (they are plugged into the wall, not an fxs port). We have 2 POTS lines plugged into the FreePBX box. We are using softphones at each computer.

The Problems:

If someone initiates a call on a “regular phone” and then someone dials out from a soft phone, Asterisk tries to place the soft phone call on the already active line. This results in the ongoing call being interrupted and the soft phone call not being completed. Is there any way for Asterisk to detect the state of a line to prevent this?

Another problem (that may or may not be related to this setup is that occasionally a line will be tied up indefinitely. I fix this by unplugging the line one from the FreePBX box and plugging it back in; which frees up the line.

You already mentioned the solution, either get two FXS ports for your existing board or pickup an external ATA.