You might need to configure the APN to use Zello. In the app, open Connection > Connection APN and choose Detect APN settings.
If this doesn't work or if you still can't create an account, you may need to contact your mobile operator for the correct settings.
We collect working settings on this page
Alternatively you can usually find the correct APN by doing an online search for "APN blackberry 'your wireless provider'".
Note that CDMA networks (like Sprint or Verizon) don't require APN settings.