Most HTC phones are able to detect which mobile operator you're using based on the SIM card you inserted, and then use the preset Access Point Name (APN) to connect to your mobile operator's data network. 
	 You can add a new (APN) when roaming or if you have difficulty establishing a data connection. 
	 
 
  
 
	 Important: Some mobile operators may not allow you to change the predefined APN or add new ones. 
			  
		  
-  
		Go to Settings.
-  
		If the Mobile data connection is off, tap the 
			 Mobile data 
			 On/Off switch to turn 
			 it on. 
		  
-  
		Tap Mobile data to open the 
		  Network settings screen. 
		
-  
		Tap 
		  Access point names. 
		 
		
-  
		On the 
		  APNs screen, tap 
		   and enter the APN settings. and enter the APN settings.
-  
		 Tap 
		   and then select the new APN on the 
		  APNs screen.