This is the easiest way to migrate from legacy Blynk projects. Just add BLYNK_TEMPLATE_ID and BLYNK_DEVICE_NAME on top of your existing firmware (before any Blynk includes), set new Auth Token and that's it. Read more about project migration.
SIMCom SIM800 series (SIM800A, SIM800C, SIM800L, SIM800H, SIM808, SIM868)
SIMCom SIM900 series (SIM900A, SIM900D, SIM908, SIM968)
Adafruit FONA (Mini Cellular GSM Breakout)
Adafruit FONA 800/808 Shield
Traffic optimization is usually required for cellular connections. Using realtime streaming protocols like Blynk or MQTT has benefits of interactive device updates, but it also requires device to stay "always connected", which significantly increases the traffic. Blynk recommends using HTTPS (batch) API for reporting telemetry and fetching DataStream values periodically in such scenarios. It will also help saving the battery.