For most users, the safest route is using the tools provided by ZTE or the original service provider. Reliance Netconnect+ 3G ZTE MF190 Drivers Download
Because it was often "locked" to specific carriers (like Airtel, Telekom, or Movistar), many users look for firmware updates to unlock the device for use with any SIM card. However, the term "firmware" can be slightly confusing in this context. Download Zte Mf190 Firmware Update