USSD codes cause a drop from LTE to HSPA or lower

[natehoy]

This isn't a huge problem but it is annoying and I hope someone can explain what is going on and why.

Whenever I use a USSD code (*DATA# for example), my phone briefly drops from LTE to HSPA or sometimes a lesser protocol. This causes a brief interruption in connection that is usually harmless, but perplexing.

I have an AT&T-model Galaxy S7 Edge and have tried this with LTE Enhanced Services turned off and also turned on. Is there another setting I should be looking at, or do USSD codes require "old school GSM" and that's just the way it is?

Thanks in advance for any insight into it.

 

[jasonandrews25788]

it's a network error.