Land line screening of calls?

Hello- 

My elderly mother(91) is a long time customer with a land line in her home.  She receives several solicitations or scam calls per week.  While she is savvy  enough not to fall for these scams, they are still upsetting.  I recently dealt with a client that had a message that came on before putting the call thru saying" This number does not accept solicitation calls.  Please remove this number from your list if this call is a solicitation.  If not, please hold while your call is put thru".

Do you have such a service?  This would greatly reduce her anxiety over these calls as she often copes by turning off her answering machine, which is not a good option