<s>
Cab	B-General_Concept
Secure	I-General_Concept
Radio	I-General_Concept
(	O
CSR	O
)	O
was	O
an	O
in-cab	O
analogue	B-Protocol
radiotelephone	O
system	O
formerly	O
used	O
on	O
parts	O
of	O
the	O
British	O
railway	O
network	O
.	O
</s>
<s>
CSR	O
was	O
replaced	O
by	O
the	O
GSM-R	O
digital	B-General_Concept
system	O
,	O
forming	O
the	O
initial	O
phase	O
of	O
rollout	O
of	O
ERTMS	O
throughout	O
the	O
UK	O
.	O
</s>
<s>
It	O
was	O
later	O
used	O
in	O
the	O
London	O
and	O
Liverpool	B-Application
areas	O
.	O
</s>
