No. You can use spell trigger items to cast spells existing within your class spell list without need of UMD checks. You can do it even if you cannot normally cast the spell.
Spell trigger magic items:
Spell Trigger: Spell trigger activation is similar to spell completion, but it's even simpler. No gestures or spell finishing is needed, just a special knowledge of spellcasting that an appropriate character would know, and a single word that must be spoken. Spell trigger items can be used by anyone whose class can cast the corresponding spell. This is the case even for a character who can't actually cast spells, such as a 3rd-level paladin. The user must still determine what spell is stored in the item before she can activate it. Activating a spell trigger item is a standard action and does not provoke attacks of opportunity.
Note that, unlike with scrolls, you are not even required to have an appropiate ability score. So the level 3rd paladin in the example can still use a cure light wounds wand even if he has Charisma smaller than 11.
What does UMD for you is to overcome the limitation of not being able to use items with spells not in your class spell list. So the paladin in the example can use UMD to use a shield wand, which usually is restricted to characters with access to the sorcerer/wizard class spell list.
Use Magic Device skill:
Use a Wand, Staff, or Other Spell Trigger Item: Normally, to use a wand, you must have the wand's spell on your class spell list. This use of the skill allows you to use a wand as if you had a particular spell on your class spell list. Failing the roll does not expend a charge.