GSM Modems

[Madars Vitolins]

Hello!

Could somebody tell me which GSM modem to choose for building SMS 
Gateway (send & receve messages) using gnokii-smsd.
I am thinking to use three such devices for load balancing.

What brands and models (up-to-date) you would recomend me? Or what 
models you have and working well?
Also I would prefer serial port based devices as they do not chang the 
ttySX X number, as I seen for usb number times to times changes...

Thanks a lot in advance!
Madars