Why can't I receive calls from land lines on my cell phone?

For the last month I can't receive calls from landlines.

All my customers and family members can't reach me via their landlines.

Cell phone call work and text is fine, its just everyone in the area using a landline can't call me.

I have customers who can't reach me now in case of an emergency. Called my Bell dealer and they can't seem to help. This is beyond frustrating. Please help!