Unable to make calls, but MMS/USSD and SMS works

I am running a [Moto G Stylus 2021](https://www.gsmarena.com/motorola_moto_g_stylus_(2021)-10583.php) . Currently, I am not able to make any phone calls, not even access my voicemail. I am though, able to receive phone calls and make and receive text messages and use USSD codes. I do not know why this is happening as it did not happen before. It is not a carrier issue because I reached out to them and they told me that they have detected no issues with my device but either way sent out a SIM refresh to my device. Even so I was still unable to make phone calls. Recent changes to my phone was someone going in and messing around with the MMI codes and settings.
Does anyone know what may be the issue?