Can someone inside Otiluke's Resilient Sphere teleport or Plane Shift away?

Question

In my answer to the question What defenses are there against being summoned by the Gate spell? the question came up whether or not someone inside Otiluke's Resilient Sphere can teleport away.

The spell states:

Nothing - not physical objects, energy, or other spell effects - can pass through the barrier, in or out, though a creature in the sphere can breathe there.

It's unclear whether or not this blocks teleportation and interplanar travel. I believe not, or at least not interplanar travel; spells that do block this usually state so, such as Forcecage. Other commenters had a different opinion, which is why I'm asking this question.

I think it ultimately boils down to:

Does teleporting or plane shifting out of Otiluke's Resilient Sphere count as "a spell passing through the barrier"?

I'm not entirely sure whether plane shifting and teleporting would be treated differently here, but I believe they might.

Answer 1

You can teleport or plane shift out of Otiluke's resilient sphere

Provided that the caster is the one inside the sphere teleport will work. Teleport has a range of 10ft so it's area of effect will be limited by the bounds of the sphere so the caster and any targets must be inside. Teleport says:

This spell instantly transports you [...] to a destination you select.

This effect is not a movement effect, you aren't passing through the sphere. You instantly appear somewhere else.

Similarly Plane Shift has a range of touch and does not require a spell effect to travel through the sphere. It says:

You [..] are transported to a different place of existence.

Traveling to another plane does not require moving through the sphere. So you can Plane Shift out of the sphere. Misty Step, Thunder Step and any other teleportation effects will all work.

Interestingly Etherealness will even let you pass through the sphere itself as you are no longer on the same plane of existance though you can percieve it. We know this because Etherealness says:

You ignore all objects and effects that aren't on the Ethereal plane, allowing you to move through objects you perceive on the plane you originated from.

As you suggest spells for which this doesn't work specifically say so, as per Force Cage's description:

If the creature tires to use teleportation or interplaner travel to leave the cage, it must first make a Charisma saving throw. On a success, the creature can use that magic to exit the cage. On a failure, the creature can't exit the cage and wastes the use of the spell of effect. The cage also extends into the Ethereal Plane, blocking ethereal travel.

Otiluke's resilient sphere does not contain similar text and spell's only do what they say they do. Therefore the sphere does not prevent teleportation of interplanar travel.

Answer 2

I think that plane shifting would be permitted, depending on how you define the Planes. Specifically, it is a sphere; that is, it exists in three dimensions. Movement beyond the bounds of the sphere in any of these three dimensions would be blocked, by the definition.

However, a plane shift does not require you to pass the bounds of the sphere, only to jump to another dimension (Plane) where the sphere does not exist. This would also permit escaping a sphere via the use of time travel, for example, as it is (strictly speaking) extra-dimensional.

Otiluke's Resilient Hypersphere, by extension, would be totally inescapable!

Under this definition, it would block teleportation, since it requires a target on the current plane of existence.