Comcast land line phone does not recognize pound sign when I try to pick up messages on my Verizon cell phone

I have ALWAYS been able to pick up my Comcast land line phone and  call my Verizon cell phone and pick up messages that were left on my Verizon cell phone. This was accomplished by dialing my cell phone and entering # during my greeting. Then entering my PIN for the cell phone. In recent weeks, when I hit # from my Comcast land line phone, nothing happens. I can retrieve messages from my Verizon cell phone using phones OTHER than my comcast land line so I do not know what is causing the problem now OTHER than an issue with the Comcast land line phone.

The Comcast land line phone is a Panasonic brand. Does anyone have any ideas on how to resolve this? Comcast support has not been able to resolve the problem. And it is not on Verizon's end.

Any assistance greatly appreciated.