If yes, can it [silent call] be done in OpenBSC or any
such way
exists to do this or any other alternative does exists?
Please check out
http://ftp.osmocom.org/docs/latest/, you can find
OsmoNiTB / OsmoMSC user manuals there. Silent call feature is
supported, but not documented. Feel free to contribute!
With best regards,
Vadim Yanitskiy.