GPRS Charges

My phone (SE T630) has options for GPRS header compression. When I've
experimented with the settings, the data counters in the phone show the
same amount of transfer.

Am I actually compressing the IP header? Do the UK networks differ on
how header compression is provided? And am I charged per 'uncompressed'
byte, or only the bytes sent over the air interface?

Apart from a (potential?) cost-saving, presumably header compression
also give a small improvement in latency. And also increases slightly
the capacity of a GPRS cell. As IPv6 is introduced, and more real-time
(i.e. small payload) services are carried over GPRS, will header
compression necessary?

(I am aware than all operators are providing data compression
on-the-fly for web pages etc. in their proxy servers - that's not what
I'm referring to).

regards,
Andrew

Andrew wrote:
> My phone (SE T630) has options for GPRS header compression. When I've
> experimented with the settings, the data counters in the phone show the
> same amount of transfer.

I would have thought the data counter is only counting the payload of
the packet, not the IP headers

> Am I actually compressing the IP header? Do the UK networks differ on
> how header compression is provided? And am I charged per 'uncompressed'
> byte, or only the bytes sent over the air interface?

Maybe the networks just count the payload and not the headers too?