Sierra Wireless 881 USB Modem (881U) and NowSMS

Posted by on Mar 17, 2009 in Support Blog

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The Sierra Wireless 881 USB Modem (881U) is a good modem to use with NowSMS.

However, it can be a frustrating modem to get properly configured.  The reason for this is because the primary market for this modem (and other USB modems) is to provide internet connectivity.
If you’re looking at using this modem (or a similar modem) with NowSMS, it’s probably best not to purchase the modem from the mobile operator with a data plan.  When you do this, they are assuming that the primary use of the modem is internet connectivity, and NowSMS will not use the modem for that purpose.  Often these data plans don’t even have SMS or MMS services enabled.
When you attempt to add the Sierra Wireless 881 USB Modem to NowSMS, you will most likely encounter the error message “Modem does not properly support command for sending SMS (AT+CMGS)”.
Or, with older versions of NowSMS, the modem will add correctly, however any attempt at sending SMS messages will result in the error “ERROR -Modem Response (1): OK”.
These errors happen because the driver software for the Sierra Wireless modems actually installs
 several virtual COM ports for communicating with the modem.
One of these ports can be used for sending/receiving SMS messages, while the other port can only support data/internet connectivity.
Older Sierra Wireless modems would install two Windows modem drivers, one for each port.
The modem driver “Sierra Wireless AirCard HSDPA Modem” would work with NowSMS and provide support for sending/receiving SMS mesasges.  However the modem driver “Sierra Wireless AirCard 3G Modem” did not work with NowSMS, and could only be used for data/internet connectivity.
With the 881U modem, multiple virtual COM ports are installed by the Sierra Wireless software.  However, a Windows modem driver is installed for only one of these COM ports, so when you select “Sierra Wireless AirCard 881U HSDPA Modem”, you are connecting to a COM port that only supports data/internet connectivity.
To be able to send/receive SMS messages, it is necessary to identify the other COM port.

To identify the COM port, go into the System applet in the Windows Control Panel, and access “Device Manager”.  In the “Ports (COM & LPT)” section, you will find a port labeled “Sierra Wireless AT Command Port (UMTS)”, followed by a COM port number such as COM8.
Once you have identified the COM port number, it is possible to add the modem to NowSMS by referencing the COM port number directly.
However, if you use the COM port directly in NowSMS, you won’t be allowed to configure the modem for sending and receiving MMS.  It will support SMS only.
The simple way to enable support for sending/receiving MMS is to manually install a Windows Modem driver for this COM port.  This can be done through the “Phone & Modem Options” applet in the Windows Control Panel.  We recommend that you manually select the modem driver, rather than having Windows detect the modem.  For best results, use the “Standard 33600 bps Modem” driver.
After installing this Windows modem driver, configure NowSMS to use the “Standard 33600 bps Modem” to connect with the Sierra Wireless 881U, instead of using the direct COM port reference.

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