1) I will hang up for now and call you back later.
2) I will hang up for now and call you again later.
1) & 2) "一旦切ってまた後でかけ直すね" という意味です.
I will hang up ：切って
for now ：一旦
and call you back later / and call you again later：また後でかけ直す
(かけ直す：to call back / to call again )
I'm going to hang up now and then call you right back
Well, it's probably not necessary to state that you will hang up. If you just say that you will call someone back, then they will understand that you need to hang up first to do that! However if time is unimportant or the level of English poor, you may prefer the third example sentence.
The phrase 'in a moment' means something that happens quickly, as does 'right back'. Both of these phrases can be used in other contexts too. For example, "In a moment the dog fell in the river" or "I'll get right back to you with the contract."
in a moment'は'right back'と同様、「すぐに」という意味です。これらはどちらも、他の文脈で使うこともできます。例えば：
"In a moment the dog fell in the river"（犬はすぐに川に落ちました）
"I'll get right back to you with the contract."（契約書を準備してまたすぐにかけ直します）
Using the word 'right' to say 'right back' indicates that you will call the person back immediately after you hang up; it lets the person know that they won't have to wait for you to call.
The two sentences you see provided above are great ways to express to your listener that you will end your call then you will call them again. In the first sentence you will notice the term call someone back. This means to return a call to someone. This is a term that is used in both formal settings and informal settings. It would make an awesome addition to your vocabulary.
When talking about something happening in a short period of time then you can say 'in a moment' or 'right back'
If you end a call you are said to 'hang up'
"I'll hang up and ring you straight back"
To 'Hang up'is an expression used when you finish a phone call.
'Ring you straight back'
to 'ring' is to call someone and 'straight back' refers to right away/soon as possible.
"I'll call you right back" is referencing that you will ring them back as soon as possible.
"I'll hang up and ring you straight back"（いったん切ってすぐにかけ直します）
'Hang up' は「電話を切る」という意味の表現です。
'Ring you straight back'（すぐにかけ直す）
'Ring' は「電話をかける」ことをいいます。
'Straight back' は「すぐに／できるだけ早く」という意味です。
"I'll call you right back"（すぐにかけ直します）は「できるだけ早くかけ直す」という意味です。
モロッコ 
イギリス 
アメリカ合衆国 
