This speculation has been published at Tech.Blorge.com blog yesterday:
http://tech.blorge.com/Structure:%20/2007/09/06/the-google-phone-may-introduce-free-cell-phone-service/

According to the entry most of the people leaving comments related to Google Phone news and speculation are missing the aspect "about Google's mode of operation: It offers nearly everything for free".

Nice idea – but highly unlikely

someone made a good analogy to newspapers (with ads) – they help reduce the cover price – and subsidise the cost of the paper which would be prohibitive if they had no ads.

jon

*ring* *ring*
"Martin Rix is Calling you"
*Beep* Buy the Apple iPhone, now reduced price *Beep*
"We will now connect you"

Hmmm could be interesting

In france, there is a plan called "Spot" : you buy a card for 1 h of call, and you get 1h free with 10 seconds ads at the beginning of your call, before ringing. Ads are chosen with the answers of a paper poll you had at your first time with Spot.

Luka
oooo would love something like this in the UK.
Is this something that's once a month or can you use it as much as you want? And you said 'buy a card' so is it free or not?

I could subscribe to that too, but I don't use it because I call nobody :) Luka is right anyway, but I thought there was also an ad every minute in the conversation. An ad for the two callers.