I Can't Receive Masterpass SMS Verification Codes, Unable to Make Purchases

For some time now, I haven't been receiving the one-time Masterpass verification codes via SMS. I wait for the verification code for quite a while, but it doesn't arrive at all, and as a result, I cannot complete my purchases. I've been experiencing this issue for an extended period, and it's causing me significant inconvenience. I would be very grateful if you could assist me in resolving this problem. I also couldn't find any relevant information or solutions on the Masterpass website regarding this issue. Could you please help me figure out why I'm not receiving the SMS verification codes and how to fix it? Your prompt assistance would be greatly appreciated.