User's Manual

GSM/GPRS Module Series
M85 Hardware Design
M85_Hardware_Design Confidential / Released 61 / 88
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 as below.
RI
Idle Ring
Off-hook by“ATA”
On-hook by “ATH”
SMS received
HIGH
LOW
Figure 41: RI Behavior of Voice Calling as a Receiver
RI
Idle Calling
On-hook
Talking
HIGH
LOW
Idle
Figure 42: RI Behavior as a Caller
RI
Idle or
Talking
URC or
SMS received
HIGH
LOW
120ms
Figure 43: RI Behavior of URC or SMS Received