Depends what model year viper you have.
FYI, it works great with Gen 3 but I heard it's a hit or miss type
of thing on Gen 4. There is a bunch of threads about this topic.
It really depends on if the adapter works with the most recent generations of ipod. If so, it should work with an iphone. If the adapter is for the earlier generations of ipod, the iphone almost certainly will not charge up, although music should be ok
When I had the Gen 3, my iphone (non 3G) worked fine without any issue.I DO HAVE GEN 3...i did see the topic's but they said nothing about iphone? im assuming iphone is like ipod?
There is a small adaptor that will allow the older systems to charge the newer IPOD systems. I think one such adapter is made by Scosche. Can not verify for you on the IPhone.