While I appreciate all the suggestions, from turn on and off airplane mode, check if number ported (not), check iPhone blocked list, do not disturb, take SIM card in and out, etc. I can assure you that none of these suggestions have resolved the problem.
For those who are experiencing the problem, I can recommend keeping track of the number of the landline that called, date and time, and inquire as to their landline phone company and then get in touch with the moderator.
I am still resolving the problem months later. This is all very frustrating and the landline phone companies are not all the same and in different locations in Canada and the USA.
this is an incoming call issue from ONLY landlines, I do not have any problems with outgoing calls.
Ok sorry. Will leave conversation. Good luck.