sierra modem connected through serial port not working

["linux.challenge1" <linux challenge1 gmail com>]

We are using Modem manager 1.8.2. We are trying to connect sierra modem via
serial port ttyS0. We modified /lib/udev/rules.d/77-mm-sierra.rules to

ACTION!="add|change|move|bind", GOTO="mm_sierra_end"
SUBSYSTEMS=="tty", GOTO="mm_sierra"
GOTO="mm_sierra_end" 

LABEL="mm_sierra"

ACTION=="add", KERNEL=="ttyS0", ENV{ID_MM_PLATFORM_DRIVER_PROBE}="1"

LABEL="mm_sierra_end"

But when we load we get following logs

syslog[4989]: <debug> [1541472622.239884] (Sierra) [ttyS0] filtered as
couldn't retrieve drivers
syslog[4989]: <debug> [1541472622.240072] [plugin manager] task 0,ttyS0:
found '0' plugins to try
syslog[4989]: <debug> [1541472622.240265] [plugin manager) task 0,ttyS0:
started
syslog[4989]: <debug> [1541472622.240424] [plugin manager] task 0,ttyS0:
finished in '1.498676' seconds
syslog[4989]: <debug> [1541472622.240912] [plugin manager] task 0,ttyS0: not
supported by any plugin

and sierra plugin is not loaded. Any help?



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