At what point should I use a call screening service?

[Benjamin Blackburn]

Hello BP,

I'm wondering if need to invest in a call screening service for my incoming calls or to just let them go to my Google Voice VM?

 My budget will allow me to probably send out about 300 pieces a month.  I do have a full-time job and at times it is difficult to step out for incoming calls. 

Thank you for any feedback.