$ sudo apt-get update
$ sudo apt-get install libgsmsd7 

libgsmsd7 is installed in your system.

Make ensure the libgsmsd7 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libgsmsd7 *

You will get with libgsmsd7 package name, version, architecture and description in a table

libgsmsd7 package basic information: