Other societal questions are relevant here such as do the people of this world have music? How much control does the average person have over their personal telepathy, meaning how much noise do they hear in their heads daily?
Also, technology can be used in different ways. The interesting bit is that what we might adore some things for now, might not be so useful for people in your telepathic world.
In our world, we take the vibrations in the air caused by sound and convert it into an electric signal. We transmit that signal to where it needs to go by some method, and convert it back to sound at the receiving end. To send words is similar, though we need to translate the text into something that can be transmitted.
As such, there is no reason why they could not develop long-ranged text communications. To them, it will be a severely impaired method of communications -- It would lack the nuance and precision of telepathy as well as being relatively imprecise.
The one big question here is since they rely on telepathy to communicate, do these people understand that enough to base a communications device around it? That has the potential to be the biggest communications game-changer.
Overall, long-range communication will be done by written words in the absence of a telepathic microphone while close-range communications will be done by telepathy.
Since telepathy follows similar rules as to speech, there would be a lack of large vocal concerts unless a telepathic amplifier was created. The microphone could still be invented if instrumental music became popular enough to warrant its development. Instrumental music can be transmitted and played, and the idea of an expression of self though music with no thought noise will be a different experience.
As such, an intimate performance with few observers can get a different interpretation of music by seeing it in person where both music and thought are played simultaneously. Poetry readings, theater, and any other live performances will be done with smaller audiences.
Without a concrete spoken language, there would be little incentive to develop television unless silent theater is a wide-spread form of entertainment and it can translate well to the screen. The technology though would still potentially exist but be primarily used for mainly surveillance purposes over entertainment ones.
Games would still exist for entertainment, though depending on the nature of the telepathy, expect more games of chance and personal skill as opposed to deductive games where a stray thought picked up can spoil the entire game. Computer games might be a guilty pleasure or something more oriented to a single player. Then again, computer co-op games could be interesting when telepathy gets involved.
The same tech that gives us television will be useful in the scientific world as it can still observe things far away. In fact, the scientific field should look similar with the exception of what is studies in what order. There might be more effort in understanding the brain or whatever your peoples use to transmit their telepathy.
Science would probably take over the written language, and develop a precision to the language that while telepathy can express it, cannot unambiguously express it. I am probably not explaining it completely right, but I am thinking of most writing as something quite precise in literal meaning as it has to compensate for a lack of telepathic context.
Computers will still be developed to make their math and calculating easier, and likely be more used for that over other tasks.
Overall, I do not really see technology changing overmuch. The biggest question is if they can develop a telepathic microphone or not. Otherwise, the tech will not focus on sound for communications and instead text and physical images.
Of course, it might be that the big invention of their 20th century is verbal language. Specifically because it is an intermediate point between telepathy and writing.