Επιλέγω είτε καρτοκινητή τηλεφωνία είτε πρόγραμμα συμβολαίου.

It means either ... or. Greek normally uses the full pair είτε A είτε B to present alternatives. In this sentence, the speaker is choosing between two options.

A simpler everyday alternative is often just ή: Επιλέγω καρτοκινητή τηλεφωνία ή πρόγραμμα συμβολαίου.

Επιλέγω is the 1st person singular present tense of the verb επιλέγω, meaning I choose or I am choosing.

Like many Greek present forms, it can mean:

• I choose
• I am choosing
• I do choose

The exact English translation depends on context.

Because the sentence is talking about types of service, not specific known items. Greek often leaves out the article when naming categories or options in this kind of context.

So this sounds like:

• choosing prepaid mobile service
• or a contract plan

If you added articles, it would sound more like specific choices: Επιλέγω είτε την καρτοκινητή τηλεφωνία είτε το πρόγραμμα συμβολαίου.

Literally, it is something like card-based mobile telephony. In practice, it means prepaid mobile service.

This is a fairly formal or commercial expression. In everyday Greek, people very often shorten the idea and say καρτοκινητό.

So a Greek speaker might casually say: Επιλέγω είτε καρτοκινητό είτε συμβόλαιο.

Because συμβολαίου is in the genitive case. Greek often uses the genitive after another noun to show a relationship like of.

So:

• πρόγραμμα = plan / program
• συμβολαίου = of contract

Together, πρόγραμμα συμβολαίου means contract plan or more literally plan of contract.

This is a very common Greek pattern:

• κάρτα μνήμης = memory card
• στάση λεωφορείου = bus stop
• πρόγραμμα συμβολαίου = contract plan

In this sentence:

• καρτοκινητή τηλεφωνία is in the accusative
• πρόγραμμα is in the accusative
• συμβολαίου is in the genitive

The accusative is used because these are the direct objects of Επιλέγω.

A useful thing to notice is that some Greek nouns look the same in nominative and accusative:

• τηλεφωνία has the same form in both singular nominative and accusative
• πρόγραμμα also looks the same in nominative and accusative singular

So the case is understood from the sentence structure, not from a visibly different ending in these particular words.

Because καρτοκινητή is functioning as an adjective modifying τηλεφωνία. It agrees with τηλεφωνία in gender, number, and case:

• feminine
• singular
• accusative

Greek adjectives often come before the noun, especially in standard neutral phrasing. Here the combination καρτοκινητή τηλεφωνία works as a set expression.

Yes, it is natural Greek, especially in a formal, commercial, or website/menu context. It sounds like something you might see when choosing a mobile plan online.

In everyday conversation, many speakers would probably use a shorter version such as: Επιλέγω είτε καρτοκινητό είτε συμβόλαιο.

So your sentence is correct, but slightly more official in tone.

Yes. Greek word order is more flexible than English word order. This sentence uses a normal, clear order, especially for instructions or menu-style wording.

You could move things around for emphasis, but the original is the most straightforward: Επιλέγω είτε καρτοκινητή τηλεφωνία είτε πρόγραμμα συμβολαίου.

If you changed the order, it might sound more marked or stylistically different rather than more natural.

Not always. In this sentence, είτε ... είτε means either ... or.

But in other contexts, είτε can also appear in meanings closer to whether or in more formal structures. Still, for a learner, the most important pattern to recognize is:

είτε A είτε B = either A or B

That is exactly how it works in this sentence.