Who I have the same questioned this topic

My company sends messages to its paying customers using phonenumber@vtext.com.  It seems that these messages recently stopped being delivered.  We use SendGrid for mail delivery, and SendGrid reports that the messages were accepted for delivery by the destination server.

I have tested this by sending messages to my own phone from different domains with different SendGrid API keys, and the messages are not received, though SendGrid's dashboard indicates that the messages were accepted for delivery by Verizon.  These domains are configured with correct SPF records, etc.  When I try sending the messages from my gmail account, they are received without issue.  Other providers than Verizon do not seem to be having this issue.

I looked at my block settings in my Verizon account and no blocks are enabled.  SendGrid's customer support indicated that this must be a Verizon issue.  I tried using phonenumber@vzwpix.com as well and still no luck.  Based on an answer I found elsewhere in the support community, I also tried phonenumbe@vzemag.biz, and that didn't work either.  Can someone please help?  Thank you.