Ubuntu 16.04:
SMSD Version 3.1.21:
Smsd installed from: sources
Name and model of a modem / phone:

Quote

Device : /dev/ttyUSB0
Manufacturer : Wavecom
Model : MULTIBAND 900E 1800 (MULTIBAND 900E 1800)
Firmware : 651a09gg.Q2406A 1480856 113005 09:42

Interface: USB

hi i have this modem https://www.amazon.com/Modem-Interface-Wavecom-Commands-Q24plus/dp/B00B8QN070 , the modem is working fine, but when i do sendsms the sendsms only use 1 simcard in my modem, how i can choose sim card to use, thank you

For choosing the modem you need to define queues, AND include a header e.g. Queue: Q1 in the message file.

The script sendsms does not handle this header, that script was made for testing purposes mainly. The application which creates message files in your system could include the Queue header, or you should modify the sendsms script.