Hospitals can't fax to one of our numbers, but can to another number?

​@Suzychapstic, 

Could you try checking your spam logs first?

Have an account admin check your Blocked Calls / Spam Log in the RingCentral Admin Portal for your main line. If you see the hospital's number listed there, simply add them to your Allowed / Trusted Numbers list.

Because main lines often have stricter spam filters than secondary numbers, RingCentral might just be flagging the hospital's fax server as a robocall and stopping it before it gets to you. Give that a look and let me know if their number shows up there.