Right, Gerd, this was also one of the documents I was refering to. Some years ago, I was working in the development department of a company building GSM mobile phones and DECT phones, so I'm absolutely sure my 8 year old DECT is using 1880-1900MHz. The ISM band at 2.4GHz is a concurrent frequency band (at least in Germany) and is used for WLAN, Bluetooth, DECT and other wireless transmissions. Therfore the availability of the band is not guaranteed and it is not a real time transmission any more.
I had a Beocom 6000 some years ago and this was attached to my Gigaset base via the GAP standard, so I suppose the BC6000 uses also 1880-1900MHz.
Keith, with the frequency range of the GSM phones I fully agree with you. DECT is the reason why GSM1900 isn't used in europe.
Marcus