Another interesting number popped up on the Internet recently. Here, Teltarif quotes Georg Benzer, Chief Network Officer for Vodafone/Arcor in Germany, saying that Vodafone/Arcor (I assume he means both their DSL and mobile network Germany) transport 1.5 petabyte a day. No more details were given and there is only one more source on the net reporting the same number. But nevertheless, let's play around with this number a bit.
The 3UK CTO recently reported that at the end of 2008, they transferred around 1.000 terabytes (=1 petabyte) a month through their wireless network in the UK. Let's say most of that traffic was generated by 3G dongles. The exact 3G dongle subscriber number of 3UK is not known, I estimate it at around half a million at the end of 2008. That means every subscriber consumed about 1.000 terabytes / 500.000 subscribers = 2 GB of data a month.
Now lets say the 1.5 petabyte a day or 45 petabyte a month in the Arcor/Vodafone network were consumed by both fixed and mobile subscribers. Let's say Vodafone Germany has 2 million 3G dongle users (just an assumption, approximated from the 3UK number, no source for this) then out of the 45 petabyte, 4 petabyte would come from mobile subscribers. That means 41 petabytes are used by fixed DSL subscribers.
The number of fixed DSL subscribers of Vodafone/Arcor Germany is reported to be around 3 million. That makes 41 petabytes / 3 million subscribers = 13.6 gigabytes per subscriber per month on average. Note that both the 2GB above and the 13.6 GB are average values and there's no telling from those numbers how many users are at both ends of that figure (i.e. how many use much less and how many use much more).
Many of Arcor/Vodafone's DSL subscribers also use their DSL line for
VoIP (with a POTS to VoIP converter at home). That traffic should not
be counted either as it doesn't leave the network, at least not as IP packets. Let's say the average subscribers uses the fixed line phone
for 5 hours a month. VoIP produces 2*80 kbit/s (uplink + downlink) = 160 kbit/s of data
traffic = 72 MB per hour or 360 MB for 5 hours. Not very much compared to the 13.6 GB per month which are just reduced down to 13.3 GB per month.
A raw comparison of the two numbers would indicate that DSL subscribers are transferring 7 times more data through their connection than wireless subscribers. But I think that is a bit too simple a view. Most wireless subscribers are likely to also have a DSL line at home and fixed and mobile use might be different. Further, DSL lines at home are often shared with family members and several devices while a 3G dongle is mostly used by a single person with only one device at a time. Also, since most wireless offers have bandwidth caps, heavy users are much more likely to use a DSL line rather than a wireless modem, thus further distorting the direct comparison.
So despite the two numbers not being directly comparable they nevertheless give an interesting indication that mobile use is is not that far away from fixed line use.