if your ISP doesn't specifically support v92, there are a 2 problems i'm aware of:
1) you may have to configure your driver to use v90 to even be able to connect to your ISP. i had to deal with this case using Corecomm before. i couldn't connect with my v92 drivers enabled, which made my modem upgrade absolutely pointless. luckily i planned ahead & bought from Best Buy. a quick trip to the local BB for a return solved the problem. i just said "it was incompatible with my PC" with a tech-free smile; then i was on my way home with a few DVD movies instead.
2) you may be able to connect to your ISP with v92 drivers, but your ISP will disconnect you as soon as the other line rings. caller ID should work in this case. i had a friend who dealt with case (2), which is not so bad for you since you can catch calls. if this is the case, be sure to turn off any prefixes that disable call waiting in your dialer location properties.
i'm not a dialup guru, but i believe case 2 is rare compared to 1. unfortunately, except trial & error experiments using a v92 modem, i don't know of any way to test if your ISP can connect with v92 drivers without them actually "supporting v92". also, as far as i know, i haven't heard of anyone being able to use connection resume with an ISP that doesn't support v92.
good luck!