I am a TN Mobile user and I'm currently away from a Wi-Fi connection. Is there a USSD code or a specific SMS format I can use to check my remaining airtime and data balance?

For TN Mobile users you can usually dial *123# or *111# to check airtime and data balance. The exact menu options vary but it works without internet.

If USSD doesn’t work sending an SMS with the word “BAL” to the operator’s service number often returns balance info. It’s old-school but still reliable when data is down.