[swinog] sdsl + isdn backup

hi all

i'm just wondering what you guys are using for bbcs sdsl lines for which customers are ordering also isdn backup.

currently we're using for cheaper solutions a zyxel 791/792 with an external isdn TA (omni.net D/omni.net lite) and as a a more expensive solution a modular cisco router with isdn and sdsl wic.

since the zyxels always making troubles - we've found more than 2 serious bugs - and zyxel forgets sometimes to fix those bugs in new firmwares and new models we're looking for a completely new solution.

are there on the market any devices which we're able to use for the swisscom bbcs service and which have a built-in isdn backup interface? ... and are below the price of ciscos... ;-)

greetings

-steven