Google Pixel 5a with Cell booster

@Sliver7  Set the Pixel 5a to LTE if that's an option. Does the phone work fine on AT&T's network outside of your home. IOW, is it on the approved whitelist for post-3G?

You might want to put the phone in the same room with the Cell Booster, turn off the phone completely, wait a few seconds, and then turn the phone back on. It could be that the phone just needs to register the Cell Booster as part of its cellular neighborhood. That's mentioned in my Tech Guide. Make sure WiFi is enabled but not WiFi-C (WiFi Calling). 

If Phone isn't sold or alpha tagged by AT&T directly... no love will be had with the microcell. Even if the phone is on AT&T's whitelist of supported phones, specific carrier configuration files must be present on the device for Wi-Fi calling or microcell support. 

I'm seeing a lot of this going on in other sites on the web. People buy up unlocked samsung, apple and Google flagship phones anywhere but AT&T, insert AT&T SIM..

No ability to Wi-Fi call nor will they link up to a "Cell Booster". There is no fix other than to obtain your phone directly from AT&T stores or online store. 

For clarification, the MicroCell worked with any phone that was registered to the AT&T network. Some phones did not work well but that was the phone design, not AT&T.

We've always purchased unlocked phones and never had any issues with AT&T/WiFi-C/MicroCell/Cell Booster. But they've all been iPhones 😉.

I ran into the same glitch indirectly. My mother has one of those phones made for seniors. Big display, emergency button, all of it. It's provisioned on AT&T network and SIM card. Here's the rub, it will not activate Wi-Fi C and will not jump on the booster at all. Get 2 blocks away from the house and it picks up on main AT&T tower.

Digging into the phone settings, I've observed it doesn't have an AT&T version of baseband or radio flash. Otherwise it's functional and runs on AT&T macro-cellular environment ok. There's no option to set LTE only on it, making me think it's just a pure 4gLTE phone and provisioning to boot, it is VoLTE capable...

But feel that deep in it's heart doesn't have the radio flashes to be 100% AT&T "transpatent". I can't seem to find any workaround. The pattern is if the phone wasn't provided and provisioned directly by AT&T with at least a 4g SIM card? You're going to have troubles.

Maybe get on touch with AT&T and have them reprovision a new SIM, they can sometimes ship dead in the box. 

VoLTE doesn't automatically mean that it is WiFi-C capable. The line needs to be provisioned for HD Voice and if it's a generic Android-based phone, there's no telling what it is truly capable of. Android-based phones always seem to have issues.

@OttoPylot I tried your suggestion (restart phone next to the cell booster). it didn't work.  I think I need AT&T to update my account with my phone.  They currently have some funny looking phone assigned to my name, like the ID (IMEI?) is incorrect. 

I also noticed that my wife can activate Wi-Fi Calling and I can't.  Just more stuff to check up on.

@Sliver7

Yes, do that.  They have the wrong imei.  Also, is your sim card old? 

@Sliver7  Yes, follow the advice mentioned by @formerlyknownas . Sounds like a provisioning or update is needed for either your phone or account.

@ottopylot @formerlyknownas 

I went to AT&T store and they updated my IMEI.  I will need to test the Cellbooster when I get home tonight.  But i've already seen a change.  before it would only do 4G.  now it is showing 5G.  so that's an improvement!  hopefully it will connect with the Cell Bosoter.  I have to call 611 to get my Wifi calling to work (sigh).  

This is a new SIM Card too.  

@Sliver7 You will need to set your phone to LTE as that is the only band that the Cell Booster will broadcast and that your phone can connect to. On my iPhone 12, I can choose between 5G Auto, 5G Only , or LTE. I keep my phone on LTE because 5G is just not reliable in my area yet. To setup WiFi-C, you need to put in your physical address as that is an FCC E911 requirement. If your address is not accepted (rural address for example) try another address that is close to you.