[Hilo] When a GPRS session is active, is it possible to disconnect the GPRS session “automatically” and do the CSD or voice call?
Answer: No. First, in the 2G word, there is no way to send/receive any CSD or voice call when there is an active data transfer in GPRS. This is a limitation from the 3GPP on the network side.
However, it is possible to receive/send CSD or voice call when a GPRS connection is established but WITHOUT any active data transfer.
While module in GPRS data mode, you can be notified by RI signal when voice call or CSD is coming. Then you can switch module from GPRS data mode to command mode by DTR or +++, then you can answer the call.
Please note that even after the call finished, the GPRS connection will still stay.
Also, when no data transfer for a GPRS call, it may be disconnected by network automatically after a few seconds or many hours depending on the network strategy.