It seems to be a term used only in Australia, since the 3 websites I found mentioning this are Australian:

Carriage service providers (CSPs)
A CSP is person that supplies a carriage service to the public using a telecommunications network unit. CSPs can include organisations that resell time on a carrier network for phone calls, provide access to the internet (Internet Service Providers) or provide telephone services over the internet (VoIP service providers). CSPs are not required to obtain a licence from ACMA to supply a carriage service to the public.
http://www.acma.gov.au/Industry/Telco/Carriers-and-service-p...

Carriage service providers
Basic definition

(1) For the purposes of this Act, if a person supplies, or proposes to supply, a listed carriage service to the public using:

(a) a network unit owned by one or more carriers; or

(b) a network unit in relation to which a nominated carrier declaration is in force;

http://www.austlii.edu.au/cgi-bin/sinodisp/au/legis/cth/cons...

I also found the translation here: http://www.linguee.es/ingles-espanol/traduccion/carriage ser...


--------------------------------------------------
Note added at 30 mins (2015-03-30 03:05:09 GMT)
--------------------------------------------------

Carrier=operador
Carriage = (servicio) portador