supported GSM modems

[Haidut]

Hi all,

Could you please send me some info on types of modems supported by
Kannel. I know the website lists some such as Siemens and Nokia but it
looks like those are not usable in the US since they operate on
different frequencies. I need a list of GSM modems that work in the US
and are supported by Kannel.
Also if you are aware of any USB-connected modems that Kannel supports
please let me know as well.
Thanks a lot.