huzaihyou no tuisekibangou wo sumaho ni hozonsite okimasita.

不在票 is the slip you get when a delivery person came but you were not home.

• 不在 = absence / not being there
• 票 = slip / ticket / form

So 不在票 is often translated as missed-delivery notice or delivery attempt notice.

In real life, you may also see similar words like:

• 不在連絡票
• ご不在連絡票
• 不在通知票

They all refer to basically the same kind of notice.

This is a noun phrase built with の:

• 不在票 = missed-delivery slip
• 追跡番号 = tracking number

So 不在票の追跡番号 means the tracking number on the missed-delivery slip.

Here, の is not just a strict English-style of. It is a very flexible linking particle between nouns. Depending on context, it can mean things like:

• possession
• belonging to
• connected with
• on
• for
• from

So in this sentence, it is most natural to understand it as:

• the tracking number from/on the missed-delivery slip

を marks the direct object of the verb.

The verb here is 保存しておきました. The thing being saved is 追跡番号.

So:

• 追跡番号を保存しておきました
• I saved the tracking number / I kept the tracking number saved

That is why 追跡番号 takes を.

Here, に marks the place or destination where something is stored.

• スマホに保存する = save it to/on a smartphone

This is similar to:

• パソコンに保存する = save it on a computer
• クラウドに保存する = save it to the cloud

If you used で, it would emphasize the tool or means:

• スマホで確認する = check it using a smartphone
• スマホで入力する = enter it using a smartphone

So:

• スマホに保存する = save it onto the phone
• スマホで保存する = less natural here, because the important point is where it is stored, not what device you used to perform the action

This is one of the most important parts of the sentence.

• 保存する = to save
• 保存しておく = to save and keep it that way for later / to save in advance

The grammar 〜ておく often means:

1. do something in advance for a future purpose, or
2. leave something in a certain state

So 保存しておきました suggests something like:

• I saved it so I’d have it later
• I saved it in advance, just in case
• I made sure to save it

This has a different nuance from plain 保存しました, which would simply mean I saved it without the strong idea of preparation or future usefulness.

The verb is in polite past because the speaker is reporting a completed action politely.

• 保存しておきました = politely saying saved it / made sure to save it

Breaking it down:

• 保存しておく = dictionary form
• 保存しておきます = polite non-past
• 保存しておきました = polite past

So the sentence sounds like someone politely telling another person:

• I’ve already saved the tracking number on my phone

Yes. スマホ is the common everyday shortened form of スマートフォン.

Both are understood, but:

• スマホ sounds more natural in casual daily speech
• スマートフォン sounds a bit more formal or full-length

So these are both possible:

• スマホに保存しておきました
• スマートフォンに保存しておきました

In ordinary conversation, スマホ is very common.

Yes. Japanese very often omits the subject when it is clear from context.

This sentence does not explicitly say I, but the natural interpretation is usually:

• I saved the tracking number on my phone

Depending on context, it could also mean:

• We saved it
• Someone saved it

But in normal conversation, listeners usually infer the subject from the situation. Japanese does not need to state I as often as English does.

Yes, the nuance is different.

• 保存しました = I saved it.
• 保存しておきました = I saved it for later / I made sure to save it in advance.

So 〜ておく adds a feeling of preparation, convenience, or anticipation of future need.

For example:

• 必要になるかもしれないので、保存しました。
  = I saved it.

• 必要になるかもしれないので、保存しておきました。
  = I saved it in advance because we might need it later.

The second one feels more intentional and practical.

Grammatically, only the 追跡番号 is marked as the object, so the sentence says that the tracking number was saved.

• 不在票の追跡番号を = the tracking number from the missed-delivery slip

It does not say that the entire slip was saved.

If you wanted to say the whole notice was saved, you would need a different object, such as:

• 不在票をスマホに保存しておきました
  = I saved the missed-delivery slip on my phone.

That might mean, for example, saving a photo of it.

No, normal Japanese is usually written without spaces like this:

不在票の追跡番号をスマホに保存しておきました。

The spaced version is probably just for learners, to make the parts easier to see:

• 不在票
• の
• 追跡番号
• を
• スマホ
• に
• 保存して
• おきました

In real Japanese text, those spaces would normally not be there.

Yes. 追跡番号 is a very standard and natural word for tracking number.

You may also see:

• 問い合わせ番号 = inquiry number / tracking number
• 伝票番号 = waybill number / shipment slip number

Which one is used depends on the delivery company or context. But 追跡番号 is very easy to understand and broadly useful.

A simple breakdown is:

• 不在票の追跡番号を = the tracking number from the missed-delivery slip
• スマホに = on/to my smartphone
• 保存しておきました = saved it for later / saved it in advance

So the structure is basically:

[object] を [place/device] に [verb]

More literally:

• I saved the missed-delivery slip’s tracking number onto my smartphone for later.

That is why the sentence feels very natural in a practical, everyday situation.