Analog Phones Loses Dialtone

I am running FreePBX-4.211.64-2-i386 with Asterisk 11.7.
I have a Sangoma (FXS) Card Count: A200=1 installed and working for inbound and outbound calls.

[[email protected] ~]# wanrouter hwprobe


Wanpipe Hardware Probe Info

1 . AFT-A200-SH : SLOT=0 : BUS=5 : IRQ=10 : CPU=A : PORT=PRI : HWEC=32 : V=13

Sangoma Card Count: A200=1

The problem is if a user unplugs their analog phone. When they plug it back in, they have lost dialtone and the only way to fix it is to reboot the PBX.

Can anyone tell me what might be the issue?

Cheers!
Dave