M66 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850MHz, EGSM900MHz, DCS1800MHz and PCS1900MHz. The M66 features GPRS multi-slot class 12 and supports the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4.

Difference B/W M66 R2.0 and M66 R1.0
M66 R2.0 does NOT support BT 3.0 while M66 R1.0 supports it.M66 R2.0 does NOT support UART GNSS while M66 R1.0 supports it.M66 R2.0 does NOT support OpenCPU while M66 R1.0 supports it.M66 R2.0 does NOT support SD card and UFS functions while M66 R1.0 supports them.

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