For several years my 3G Microcell gave me 5 bars on my phone, but not now.

[AC Question]

Recently, my 3 G Microcell quit working and I had to switch to Wi-Fi calling. Is something wrong with my phone?

 

[belodion]

Possibly. Try removing the SIM and cleaning the contacts, such as with a pencil eraser. Reinsert and try again.
Other things worth trying are a Power Off & Restart, and toggling Airplane Mode on and off.
Tell us what happens.
https://forums.androidcentral.com/showthread.php?t=409154