What about Wi-Fi calling? That may be another option worth exploring if the booster isn't available.
As I stated in my original post, I have no internet service hence no Wi-Fi.
I'm sorry you haven't had any luck getting answers on the proper signal booster you need. We've chatted about it a lot here on the Support Community because users weren't receiving the Signal Booster DUO, but instead just the regular signal booster. From doing some digging, the 700 MHz isn't in stock and we don't have any info on when they'll be available. As far as a wait list goes, I'm not aware that we have one. You have the correct model number listed at the end of your post, but again, we don't know when they'll be restocked. From what I understand, you can only qualify for this booster if you're in an area that only supports 700 MHz and not other bands like 1900/2100 MHz.