[LinuxBender]

There are very few sites I would even remotely trust to give my number to. For starters, sites get hacked all the time and sim-swappers use this information to decide what numbers to steal assuming the site has something that converts to real currency or provides some additional information that can be used to access financial data or providers the attacker with a way to anonymize further crimes. This is partially the fault of the passive-aggressive lazy wireless industry and legislation around portable numbers.

If it's a brick and mortar business that is local to me and I can walk in if there is an issue with my phone then I might consider it. Even then I disable web access to anything financial if it's an option with that business. The local grocery store for example has my Skype-In number and that forwards to my cell. There are a limited number of businesses that will send SMS to Skype however since it is VoIP and is rife with abuse. I am less concerned with attackers learning my Skype number.

So if your business officially supported sending SMS to a VoIP number and officially stated that so I did not have to be worried some day your business would cut me off when it decided to not support Skype-In then I would probably use it. If an actual cell is required I would not likely participate but I am a bit jaded after seeing everything that can and will go wrong on the internet. I will not install a websites application on my phone.