This was not a representative sample survey like Teleuse @ BOP, but still it was conducted in a remote village in the Polonnaruwa district in Sri Lanka as part of a community communication effort. The numbers they came up with were much higher than ours.
We also spoke about the advantages of using mobile phones to complement the radio productions. 3G was not present in all areas, and in any case, few of the handsets supported audio streaming. That said, the production team said that upwards of 95% of all households owned at least one mobile.