The signal indicator on my phone often shows “3G” or “H+” in the signal indicator. When there’s no connectivity it doesn’t show anything.
They are referring to the mobile data connection:
- G : GPRS (slowest, data rates of 56–114 kbit/s)
- E : Edge (enhanced GSM, data rates up to 236 kbit/s )
- 3G : UMTS (data rates up to 384 kbit/s)
- H : HSPA (enhanced 3G, data rates up to 14.4 Mbit/s)
- H+ : HSPA+ (even more enhanced/faster HSPA, data rates up to 42 Mbit/s)
- 4G : LTE (Long term evolution, data rates up to 300Mbit/s)
Note : all data rates mentioned are downlink peak rates. Uplink data rates are much lower.