Setting up a phone line to receive texts

We want to use one of our Zoom phone lines as a dedicated line for receiving text (SMS) messages.  The idea is that families we support (we’re a charity) could send a text to that line and one of our volunteers would call them back or respond by text using their own phones (not the Zoom phone).  I have acquired the Zoom phone number, but am having trouble figuring out how to set it up to receive SMS messages.  Everything I see in the Phone section of the Zoom Web Portal seems oriented around setting up SMS campaigns, which seem to be for outgoing text messages.  In this case we just want to use it to receive texts.  Zoom Help has been no help.  Can anyone tell me what to do so we can start receiving texts on that phone line?  Thanks!