On this page:

http://maps.aa.co.nz/traffic/carnav

They state that navman pna's can receive RDS-TMC traffic updates and certain TOMTOM pna's use the vodafone network.

Since TOMTOM make external RDS-TMC receivers. i.e:

http://www.tomtom.com/en_gb/products/accessories/antennas-receivers/rds-tmc-traffic-receiver/

I am wondering whether I could purchase one of these in order to get the RDS-TMC updates with my existing TOMTOM pna.

Can anyone tell me whether this would work? I'm not asking whether the receiver will work with my device, but whether the receiver will work with the RDS-TMC broadcast or whether it's somehow navman specific?

The reason I ask is that my sister is currently in the UK and could bring one back for me.