Samsung S21 Call Issues

[Android Central Question]

My S21 phone is originally a Verizon 5G carrier phone but I switched back to cricket 4G since it's cheaper, I haven't had issues until about 2 weeks ago when I can't receive calls or call anyone on the phone. I've been searching on Google on how to fix this and I've tried every way except using the supplementary services. The only issue with that is that when I go to my phone settings there is no "supplementary services" option. How can I access this setting?