It's recommended that connect Android phone instead of modem to send MMS. Most of carriers block the MMS from modems.
Config Android phone for MMS
Add Android phone connection
Select correct country and operator
click button 'Add' to save the connection to phone list
Config modem for MMS
MMS need a standard GPRS/3G connection to be initiated over a modem. When you connect your GSM modem to the computer, Please make sure install the appropriate windows modem driver from the device manufacturer. Only modems that have a windows modem driver defined for the modem can be used. Normally windows will list them on device manager->Modems, when you create MMS connection , the modem can be listed on modem configuration windows, refer to below screen shot:
Some multiple ports modem have not provide modem driver, You may use the “Standard 33600 bps modem" driver that is built into windows. Refer to below steps,
Open Windows control panel and click 'Phone and Modem'
Click 'Add' to add modem, please checked option 'Don't detect my modem, i will select it from a list'.
Select 'Standard 33600 bps Modem'
Note: if your manufacturer column is empty, please download windows modem driver via http://www.smsdeliverer.com/download/win_modem_driver.zip
uncompress zip file then click button 'Have disk' to specify driver file.
Select the COM port number what is the modem used.
Click finish, Windows will add this modem, you may double check it from device manager->Modems.
Finally: Switch to SMS Deliverer, when creating MMS connection you may select this modem via modem list.