Quectel M66

GSM/GPRS Module Series
M66 Hardware Design
M66_Hardware_Design Confidential / Released 52 / 80
If the module is used as a caller, the RI would maintain high except the URC or SMS is received. On the
other hand, when it is used as a receiver, the timing of the RI is shown below.
RI
Idle Ring
Off-hook by “ATA”
On-hook by “ATH”
HIGH
LOW
SMS received
Figure 34: RI Behavior of Voice Calling as a Receiver
RI
Idle Calling
On-hook
Talking
HIGH
LOW
Idle
Figure 35: RI Behavior as a Caller
RI
Idle or
Talking
URC or
SMS received
HIGH
LOW
120ms
Figure 36: RI Behavior of URC or SMS Received
120ms, then changes to HIGH.
URC
Certain URCs can trigger 120ms low level on RI. For more details, please refer to
the document [1]
Quectel
Confidential