<s>
CSipSimple	B-Application
is	O
a	O
Voice	B-Application
over	I-Application
Internet	I-Application
Protocol	I-Application
(	O
VoIP	B-Application
)	O
application	O
for	O
Google	B-Application
Android	I-Application
operating	O
system	O
using	O
the	O
Session	B-Application
Initiation	I-Application
Protocol	I-Application
(	O
SIP	O
)	O
.	O
</s>
<s>
It	O
is	O
open	B-Application
source	I-Application
and	O
free	B-Application
software	I-Application
released	O
under	O
the	O
GPL-3.0-or-later	B-License
license	O
.	O
</s>
<s>
Support	O
for	O
IPv6	B-Protocol
–	O
If	O
the	O
hardware	O
,	O
Android	B-Application
version	O
,	O
ISP	O
and	O
all	O
other	O
parts	O
of	O
the	O
connections	O
involved	O
can	O
handle	O
IPv6	B-Protocol
,	O
then	O
Csipsimple	B-Application
can	O
be	O
used	O
to	O
make	O
direct	O
end-to-end	O
ipv6-to-ipv6	O
calls	O
.	O
</s>
