Question about music host sites and phone support?

 
   I use Bandcamp and started using SoundCloud to host my music. I have several friends who only connect to the internet with their phones. Some of them use Verizon Phones, others IPhones and a few other types. 
 
My question is, it seems most of what I post on Bandcamp and SoundCloud they can't seem to be able to listen to my music on their phones. 
 
What is the most phone friendly site to post music on where they can hear my music over phones, mainly for a Nokia Verizon Phone?
 
I don't have a smart phone and know next to nothing about them. I've been told they have to install an App in a lot of cases for them to be able to hear music on certain sites? Is that a requirement for all sites to be able to hear music over the phone?