<s>
Osmocom	B-Application
(	O
open	B-Application
source	I-Application
mobile	I-Application
communications	I-Application
)	O
is	O
an	O
open-source	B-Application
software	I-Application
project	O
that	O
implements	O
multiple	O
mobile	O
communication	O
standards	O
,	O
including	O
GSM	O
,	O
DECT	B-Protocol
,	O
TETRA	O
and	O
others	O
.	O
</s>
<s>
In	O
2008	O
Harald	O
Welte	O
and	O
Dieter	O
Spaar	O
experimented	O
with	O
a	O
base	B-General_Concept
transceiver	I-General_Concept
station	I-General_Concept
from	O
Siemens	O
that	O
was	O
end-of-life	O
and	O
implemented	O
the	O
BSC	O
side	O
of	O
the	O
A-bis	O
protocol	O
,	O
which	O
eventually	O
turned	O
into	O
OpenBSC	B-Application
.	O
</s>
<s>
After	O
attracting	O
more	O
interest	O
,	O
support	O
for	O
other	O
BTS	B-General_Concept
models	O
was	O
added	O
.	O
</s>
<s>
The	O
first	O
release	O
of	O
the	O
OpenBSC	B-Application
project	O
took	O
place	O
at	O
the	O
25th	O
Chaos	O
Communication	O
Congress	O
held	O
in	O
December	O
2008	O
.	O
</s>
<s>
Together	O
with	O
OpenBSC	B-Application
,	O
these	O
projects	O
became	O
part	O
of	O
the	O
new	O
Osmocom	B-Application
umbrella	O
project	O
.	O
</s>
<s>
The	O
Sysmocom	B-Application
GmbH	O
company	O
was	O
founded	O
by	O
Welte	O
and	O
Holger	O
Freyther	O
in	O
2011	O
to	O
provide	O
commercial	O
support	O
.	O
</s>
<s>
Since	O
2018	O
Osmocom	B-Application
software	O
and	O
Sysmocom	B-Application
hardware	O
has	O
been	O
used	O
in	O
Villa	O
Talea	O
de	O
Castro	O
in	O
Mexico	O
to	O
provide	O
a	O
cellular	O
network	O
to	O
around	O
3500	O
people	O
.	O
</s>
<s>
Osmocom	B-Application
software	O
has	O
been	O
used	O
in	O
research	O
projects	O
.	O
</s>
<s>
OpenBSC	B-Application
was	O
a	O
project	O
to	O
develop	O
a	O
free	B-Application
software	I-Application
implementation	O
of	O
GSM	O
protocol	B-Protocol
stack	I-Protocol
and	O
elements	O
.	O
</s>
<s>
It	O
runs	O
on	O
Linux	O
and	O
requires	O
an	O
E1	O
interface	O
(	O
ISDN	O
Primary	B-Protocol
Rate	I-Protocol
Interface	I-Protocol
,	O
via	O
mISDN	O
)	O
.	O
</s>
<s>
It	O
is	O
written	O
in	O
C	B-Language
and	O
licensed	O
using	O
the	O
GPL	O
( ≥v2	O
)	O
license	O
.	O
</s>
<s>
The	O
first	O
version	O
implemented	O
the	O
GSM	O
specification	O
21.12	O
and	O
08.5x	O
,	O
and	O
worked	O
for	O
a	O
specific	O
Base	B-General_Concept
Transceiver	I-General_Concept
Station	I-General_Concept
(	O
Siemens	O
BS11	O
MicroBTS	O
)	O
.	O
</s>
<s>
OpenBSC	B-Application
implemented	O
several	O
MSC	B-Device
components	O
,	O
including	O
the	O
A-bis	O
protocol	O
(	O
the	O
protocol	O
between	O
the	O
BTS	B-General_Concept
and	O
the	O
BSC	O
)	O
,	O
AUC	O
,	O
HLR	O
,	O
VLR	O
(	O
both	O
using	O
SQL	B-Language
tables	O
)	O
,	O
and	O
a	O
SMS	O
Switching	O
Center	O
.	O
</s>
<s>
OpenBSC	B-Application
can	O
be	O
accessed	O
using	O
telnet	B-Protocol
.	O
</s>
<s>
OpenBSC	B-Application
supported	O
the	O
following	O
BTS	B-General_Concept
devices	O
:	O
</s>
<s>
OpenBSC	B-Application
is	O
now	O
considered	O
legacy	O
and	O
the	O
features	O
have	O
been	O
split	O
into	O
different	O
projects	O
:	O
OsmoBSC	O
,	O
OsmoMSC	O
and	O
OsmoHLR	O
.	O
</s>
<s>
OsmocomBB	O
implements	O
the	O
GSM	O
protocol	B-Protocol
stack	I-Protocol
's	O
three	O
lowest	O
OSI	O
Layers	O
of	O
the	O
client	O
side	O
GSM	O
protocol	O
and	O
device	B-Application
drivers	I-Application
.	O
</s>
<s>
The	O
protocol	O
layers	O
forming	O
the	O
kernel	O
exists	O
on	O
the	O
baseband	O
processor	O
,	O
typically	O
consisting	O
of	O
an	O
ARM	B-Architecture
processor	I-Architecture
and	O
a	O
digital	B-Architecture
signal	I-Architecture
processor	I-Architecture
.	O
</s>
