mobile

I just updated to Android 5.02. I currently use T-Mobile's legacy Pay-as-you-go service because I'm only in the US for short periods and have a significant balance to use before I'll look at changing my plan. Since updating I've started to get a message asking me to "sign in" to T-Mobile. I also noticed that a small "E" appears in the upper left of the signal strength indicator (see the attached screen shot). If I respond to the "sign in" request I'm directed to update my service. If I do nothing, everything works as it should and the "sign in" icon and "E" disappear in a few minutes. Is there a setting for the T-Mobile service on the phone that I should change? Are there directions somewhere that show the legacy settings I should be using?

Thanks in advance.

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