I think it definitely has a use in some cases.
The use is to get the person on the other end of the line to actually stop talking so you can end the call.
Usually one starts signalling a desire to end the conversation by abandoning substantive answers in favor of simple affirmatives, transitioning at last to repeated versions of good-bye .
Here's how such a dialogue sounds from that side of the conversation:
Yeah, that's a great idea
, I'll take a look ...
yeah ...
uh-huh
... I'll have a look ... uh-huh
...
yeah ...
yeah ...
uh ....
uh, OK ...
OK ... OK, talk to you later ...
bye .... bye-bye.
[Hangs up]
I made up my own term to describe this kind of dragged-out phone-call-ending: conversational dieseling (from dieseling as used in automobile parlance).
english.stackexchange.com/users/2303/Robusto
You can definitely say "see you later" or "talk to you later" as the final utterance before ending your conversation.
You can add "bye" afterwards if you choose — it wouldn't sound strange, but it is not needed.
The other person may respond with "bye" (but could also say other things like "see you"), but it is not necessary for you to then say "bye" in return if you have already said "see you later" (although there is nothing wrong with it).
english.stackexchange.com/users/449/Kosmonaut
It is redundant from an information standpoint as you communicated your desire to hang up.
With that being said, however, phone conversations can have tricky social protocols that vary from place to place.
Many people treat a mutual bye (or goodbye ) as a necessary step to end a conversation politely.
(Think of it as an informal, though widespread, voice procedure .)
Usually it manifests something like the following: A:
Ok, I'll talk to you later.
B:
Alright, bye.
A: Bye Mutual Hangup.
In some locales, its common on calls to friends/family to make up an excuse for why you need to end the conversation, even if its obvious to both parties that you've just run out of things to say.
Presumably, this is due to wanting to be especially polite and indicate that you find the person so delightful that you'd love to just keep chatting away if it wasn't for that darn cat that needed to be let out or dishes that needed to be washed, etc.
english.stackexchange.com/users/2007/Dusty
Yes it's redundant, and yes it's annoying, but my mother (sorry Mum) does it all the time.
I speculate it came about as a way of softening potential awkwardness when terminating a phone conversation.
So, rather than simply hang up, my mother (for instance) repeats (more than once) the word "bye" in a decreasing volume and tone, thus blurring the end of the exchange, until one or both hang up.
That, or its a nervous tic.
Oh, and also see this .
english.stackexchange.com/users/588/Ed Guiness
"See you later" and "bye" may be redundant in meaning; however, they have some meaning if you examine the different levels of discourse in a conversation.
Here are two discourse-level observations.
First, the sentences in conversations tend to get shorter to signal its end.
(For example, think of a couple having a conversation in which one party answers in monosyllables.
He may be indicating that he wants the conversation to end.)
Second, there are no gestures or body language over the telephone.
The parties are signaling their mutual desire to end the conversation without recourse to the gestures of shifting weight, pointing feet toward the door, closing a notebook, or getting up.
"OK, talk to you next week." "OK, See you."
"See you."
"Bye." Hope that helps.
Bye.
english.stackexchange.com/users/3306/rajah9
Since 'bye' is a shortened version of 'good bye', which is derived from Middle English 'godbwye', meaning "God be with ye", it is not out of line to say "See you later, bye", litterally "See you later, God be with you."
english.stackexchange.com/users/3800/oosterwal
In conversation, what is heartfelt is never redundant.
But what is said out of habit and often repeated each time can be redundant.
"
See you later"/"talk to you later", if used to inform and supply some yet unknown intention, is not redundant.
But "talk to you later" used to inform one's purposeful intention to call someone back that evening, is necessary information and therefore not redundant.
english.stackexchange.com/users/49488/Julie
Are the closing greetings "see you later", "talk to you later", and the like sufficient to end a conversation (especially a phone conversation) or must they be succeeded by "bye" or another word of definite finality?  In other words, is it redundant to append "bye" to "speak to you later" or a similar wish?
Is it redundant to append "bye" to "speak to you later"?
english.stackexchange.com
<conversation><greetings>
english.stackexchange.com/questions/11690
english.stackexchange.com/users/2396/WAF
It is generally considered that "talk to you later" can be used as the final utterance before ending a conversation. "Bye" can be added afterwards and wouldn't sound strange, although it is not needed. It can also be used to get the person on the other end of the line to actually stop talking. From an information standpoint the word "bye" is redundant, however, many people treat a mutual "bye" as a necessary step to end a conversation politely. These phrases are useful to help end a call.  "see you later" can indeed be used after "bye" and it may be reciprocated. It is a redundant if you have already explained your desire to hang up but they are polite social conventions and these can vary geographically. Some believe that a mutual "bye" must occur for a conversation to end. It may be a need to reduce any awkardness. "see you later" and "talk later" may also be real confirmations to indicate the desire to meet up again/talk again. Although we understand "bye" to mean ending a conversation, originally it meant "God be with you" and so would not be a defintive termination of a discourse along with "see you later". The  individual's preference is probably the best choice in the end.
It is generally considered that "talk to you later" can be used as the final utterance before ending a conversation. "Bye" can be added afterwards and wouldn't sound strange, although it is not needed. It can also be used to get the person on the other end of the line to actually stop talking. From an information standpoint the word "bye" is redundant, however, many people treat a mutual "bye" as a necessary step to end a conversation politely. The final words can have a literal meaning in some cases, but are usually just polite ways to signal the end of a conversation. You could add 'bye' or end the conversation after 'talk to you later', since both have a similar pragmatic function.
It is not needed and is redundant to add "bye" after "see you later", but it doesn't sound strange. Bye can be seen as a necessary step to end a conversation.  Saying "Bye" after saing "See you later" could be considered redundant, but using it will not be a problem. However, some people might argue that, give the literal meaning of the word "bye", it does still have a use.
It is useful to help end the call. It is ok to use, as final or as penultimate sign off. Not necessary logically, but as a polite social convention  Nerovous tic Etymologically, it has a different meaning to what we think If it is sincere, it is not redundant, but repetition or habit could make it so.
The final words can have a literal meaning in some cases, but are usually just polite ways to signal the end of a conversation. You could add 'bye' or end the conversation after 'talk to you later', since both have a similar pragmatic function.
Adding "Bye" to the end of a conversation after saying "See you later" is not problematic. When considering the informational content, "Bye" could be considered redundant. If we consider the literal meaning of "Bye", it could be considered to have its use.