The wizard can track the demon and summon them yes. More powerful demons can sense their master over the link…however MOST can not activate the link without a summoning spell from their accursed master.
The vast majority of demons can’t make it to the planes of men without a wizard. I point out that Antefalken requires Damien to summon him, I had to hitch a ride with Tom. Tom can only do it if he can locate a summons to hijack (a very rare trick) or in the case of the ring, he was able to follow a link tied to his true name.
In fact, the speaking of a demon’s true name is historically well known to attract the demon’s attention and the more powerful ones might then show up of their own volition (this is the subject of a lot of horror movies)
E.g. speaking the name three times in a mirror is always inviting trouble in when IV or higher is involved.
However, that is really only the 4.5’s and above, i.e. the direct mana manipulators. And not all of them.
Remember, Ramses and Exador are an Animage and Wizard respectively, so what they can do may or may not be tied to their demon abilities.
But a Type II demon can no more jump between planes than a master jeweler or a chef.