User's Guide

The Operational View SB300 Series
Page 60 Proprietary and Confidential 2110059 Rev 1.1
6.3. Originate a CSC Connection
CSC operates just like regular landline modems except the call is placed over a cellular network.
Watcher (Section 0) can be used to setup the modem for CSC operation. When set, a call can be
placed using any modem application which can issue a dial command to the port.
Alternatively, Windows Dial-up Networking can be configured to establish a connection. If Dial-
up Networking (or any other communication application) is used to setup the modem, the setup
string should be:
AT &F5
This command will configure the modem to use ETC settings that improve performance for
cellular connections. See Section 6.5 below for a full discussion of optimized cellular settings.
You may freely add necessary settings to control the local DTE/DCE interface (echo, verbose,
quiet, etc.) without altering the remote connection settings.
6.4. Auto-answer a Cellular Call
Your application can use the modem just like any landline modem. The modem setup string
should be:
AT &F5
AT S0=n where n is the ring count on which the modem will answer the line.
This setup will configure the modem to use ETC settings that improve performance for cellular
connections. See Section 6.5 below for a full discussion of optimized cellular settings.
You may freely add necessary settings to control the local DTE/DCE interface (echo, verbose,
quiet, etc.) without altering the remote connection settings.
6.5. Optimizing Data Performance
The SB320 modem can be configured for excellent cellular performance. The AT&T Paradyne
Comsphere product line is recommended as the landline side. Alternatively cellular modem pools,
sometimes supplied by the cellular service provider are normally good for performance, although
they too need to be properly configured by the cellular carrier to optimize the performance.
The SB320 modem supports V.34 protocol allowing it to achieve higher connection speeds, and to
optimize its filter characteristics dynamically to get the best Signal-to-Noise Ratio (SNR) on a
given link. This makes for a much more robust and faster connection and speeds of 19200 bps are
not uncommon with this modem if the host supports V.34 as well.
To help determine the nature of the connections being established in trials it may be useful to have
the modem report a more extensive reply. Setting S95=127 will enable the modem to report the
DCE connection speed, protocol, and compression negotiated.
A number of connection scenarios between a SB320 and a variety of host modems are considered
in the following sections in an attempt to present a guideline to improve connectivity. The host
modems are divided in two categories: those that support ETC and those that don’t. Of those
modems that don’t support ETC, a further differentiation is made with regard to those that support
LAPM/V.42bis and those that don’t. Finally, modem pools with *DATA service are considered
as a separate category, even though these modems do implement ETC.
But first the factory settings are described as a reference point.