Have the same problem with Teltonika 950.
An error taken from the "...SIM Management/Read SMS" option.
I wonder if the bug was before the update but it probably wasn't. There has been no update to the last firmware
RUT9XX_R_00.06.07.4
Tampering with "used" or "available" 20 has no effect.
Sorry, the server encountered an unexpected error.
/usr/lib/lua/luci/dispatcher.lua:224: Failed to execute template dispatcher target for entry '/admin/services/sms/sms-manage/inbox'.
The called action terminated with an exception:
/usr/lib/lua/luci/template.lua:17: Failed to execute template 'sms-utilities/sms-manage'.
A runtime error occured: /usr/lib/lua/luci/tools/status.lua:73: attempt to compare number with nil
stack traceback:
[C]: in function 'assert'
/usr/lib/lua/luci/dispatcher.lua:224: in function 'dispatch'
/usr/lib/lua/luci/dispatcher.lua:98: in function