تذكرة الدخول عالتلفون.

Because this is a normal present-tense nominal sentence in Levantine Arabic. In the present, Arabic usually does not say is / am / are.

So:

تذكرة الدخول عالتلفون literally looks like the entry ticket on the phone,

but it naturally means:

The entry ticket is on the phone.

If you wanted past or future, you would usually add a verb such as كان:

• كانت تذكرة الدخول عالتلفون = The entry ticket was on the phone.
• رح تكون تذكرة الدخول عالتلفون = The entry ticket will be on the phone.

It is an iḍāfa construction, often called a construct phrase.

It is made of:

• تذكرة = ticket
• الدخول = entry / admission / entering

So literally it is:

ticket of entry

In natural English, that becomes:

entry ticket or admission ticket.

Also, الدخول here is not a verb. It is a noun (more specifically a verbal noun), meaning entry or admission.

That is how iḍāfa works in Arabic.

In an iḍāfa:

• the first noun usually does not take الـ
• the whole phrase gets its definiteness from the second noun

So:

• تذكرة الدخول = the entry ticket
• تذكرة دخول = an entry ticket / entry ticket

Even though تذكرة has no الـ, the phrase is definite because الدخول is definite.

Yes. عالتلفون is the spoken, contracted form of على التلفون.

In Levantine, على is very often reduced to عَ in everyday speech. When it comes before الـ, people commonly write and say it as one chunk:

• على التلفون
• عَ التلفون
• عالتلفون

All of these point to the same basic idea: on the phone.

Because ت is a sun letter.

When الـ comes before a sun letter, the ل sound is absorbed into the next consonant. So:

• التلفون is pronounced more like اتّلفون
• عالتلفون is often pronounced more like عتّلفون

The spelling usually still keeps the ل, but the pronunciation changes.

The same thing happens in الدخول:

• written: الدخول
• pronounced more like: اددخول / id-dukhool

So the written form and the spoken form do not always match exactly.

Because Arabic often uses على for things shown or available on a screen or device, much like English says on the phone.

So عالتلفون sounds very natural for:

• a ticket displayed on the phone
• a barcode on the phone
• something you can show from your phone

في التلفون can sometimes be used too, but it can sound more like in the phone, as in stored inside it. In this sentence, عالتلفون is the more natural everyday choice.

تلفون is normal and widely understood in Levantine.

But in everyday speech, many speakers also say:

• موبايل = mobile / cell phone

So you may also hear:

تذكرة الدخول عالموبايل

That is very natural too.

By contrast, هاتف is more formal or Modern Standard Arabic. In daily Levantine conversation, تلفون and موبايل are much more common.

A common Levantine-style pronunciation would be something like:

tazkret id-dkhool ʿat-tilifoon

Depending on the region, you may hear slightly different vowels, for example:

• tazkarit
• tazkret
• telefon
• tilifoon

The important things to notice are:

• تذكرة often sounds like tazkret in connected speech
• الدخول is pronounced with assimilation: id-dkhool
• عالتلفون often sounds like ʿat-tilifoon

You would usually remove الـ from تلفون when you add a possessive ending.

For example:

• تذكرة الدخول عَ تلفوني = The entry ticket is on my phone
• تذكرة الدخول عَ تلفونك = The entry ticket is on your phone
• تذكرة الدخول عَ موبايلك = The entry ticket is on your mobile

Notice that with a possessive suffix, you usually do not say عالتلفوني. The simpler pattern is:

عَ + noun + possessive suffix

It sounds mainly like spoken Levantine.

The biggest clue is عالتلفون, which is very colloquial in both form and feel.

A more formal or Standard Arabic version might be:

• تذكرة الدخول على الهاتف

But in real-life spoken Levantine, the given sentence is very natural.

Also, in conversation, native speakers might make it even shorter if the context is obvious, for example:

• التذكرة عالتلفون = The ticket is on the phone
• عالتلفون = It’s on the phone

So the sentence you have is a very normal spoken-style way to say it.