User Manual

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2009 Industrial Wireless Guidebook
Cellular Networks
3
Short Message Connection (SMS Tunnel)
Short Message Service (SMS) is a very popular service offered by cellular providers. You can send and
receive serial data via SMS by setting up the OnCell G3100 device’s SMS Tunnel Mode.
The OnCell G3100’s SMS Tunnel Mode uses a serial port to serial port communication tunnel to send SMS
messages. There are 3 key inputs involved in transmitting SMS serial data.
1.Target phone number of the mobile device that will receive transmitted data
2.Pre-approved recipient phone numbers; unapproved numbers will be filtered out
3.Data format (i.e., ASCII, binary, UCS2)
Unlike GPRS and CSD, SMS employs a “store and forward” mechanism so messages are not transmitted in
real time.
IP Gateways and CSD
Some cellular providers offer Circuit Switch Data (CSD) service, which transmits data over voice channels
that are always connected, such as fax and modem service. However, CSD calls always occupy the phone
which means you will still be charged for service even when you are not sending data. In additional, data
throughput is limited and takes up too many resources. As a result, cellular providers usually do not offer
CSD and the service is no longer offered in some countries. At the same time, 2G service is also being
phased out in favor of 3G technologies. Check with your cellular provider to see if they offer these services.
The OnCell G3100 IP gateway can send IP stacks using PPP (Point to Point Protocol) capability over CSD
service. There are 2 mechanisms for setting up your PPP connection:
1. The originating OnCell device (PPP) dials the terminating OnCell device (PPPD).
PPP(Dial out) to PPPD(Dial-In)