I guess this is because you have mapped your virtualhost to www.dummy-host.example.com
and it won't work to access the server using only its IP-address. You will need to add a mapping between the servers IP-address and server alias. This could easily be done by adding a new line into your /etc/hosts
file on you client machine i.e:
192.168.1.1 www.dummy-host.example.com
Since you're using a phone you won't be able to edit any hosts file and then you could use IP-based virtual hosts or perhaps a setup a local DNS server.
Here are a couple of links with different solutions for this problem