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Hello, H Open Readers!

A useful test that we can perform from the VTY is to send a text message to a subscriber:

OpenBSC# subscriber id 1 sms send Hello, H Open Readers!

Sending an SMS from the OpenBSC NITB VTY
Zoom Sending an SMS from the OpenBSC NITB VTY and the resulting log messages

A text message
Zoom A text message sent from the OpenBSC NITB VTY

With a second handset provisioned – this subscriber has been given the extension 1004 and a friendly name of Ben – we can make calls.

Call established
Zoom A call established via the sysmoBTS and OpenBSC NITB

OpenBSC NITB log messages
Zoom OpenBSC NITB log messages resulting from 1004 calling 1003

GSM uses time-division multiplexing (TDM) to divide a radio channel into 8 timeslots and the OpenBSC default is for 6 of these to be configured to carry voice calls. These are timeslots 2-7 and, while the call is in progress, we can use the monitor firmware to confirm that timeslot 2 is in use by one handset and timeslot 3 by the other.

With the call in progress we can also use the VTY to view resource usage at the level of the network and the BTS.

Output of the show network command
Zoom Output of the OpenBSC CLI show network command during a call

Output of the show bts command
Zoom Output of the OpenBSC CLI show bts command during a call

Next: Practical use

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