Enable Portable Hotspot on iPhone 4/4s/5
Settings>Cellular> in Cellular Data should be turn on (in case LTe is available you can enable it too)
Scrolling down the Cellular menu you can see Cellular Data Network, tap it to see the current configurations.
MMS Max Message Size:307200
MMS UA Prof URL
Note: You should use prepaid APN on Personal hotspot, in my case I'm using Globe so I use http.globe.com.ph. For Smart, Sun Cellular and other networks, you can do the same procedure just make sure you're using their respective APN.
Once you're done with above settings you can now go back to Cellular menu
Tap on Personal hotspot>Swipe the switch on to enable your portable hotspot
On Wifi Password, set your desired WiFi hotspot password for security.
To change your Wifi hotspot name
Go to settings>General>then tap on About, on the Name field change it to your desired name e.g myiPhone Hotspot.