Τηλεφωνώ στη μαμά μου όταν γυρίζω σπίτι.

Στη is just the contracted form of σε τη.

• σε = to / at / in
• τη = the (feminine accusative singular)

So:

• σε τη μαμά μου → στη μαμά μου

In normal modern Greek, the contracted form στη is what you usually say and write.

Yes. στη μαμά μου means to my mom.

The verb τηλεφωνώ works with σε + noun/pronoun, just like English phone/call someone, but Greek expresses it as phone to someone.

So:

• Τηλεφωνώ στη μαμά μου = I call my mom
• literally: I phone to my mom

That is why you see σε / στη here.

In Greek, possessive weak pronouns like μου usually come after the noun.

So:

• η μαμά μου = my mom
• ο φίλος μου = my friend
• το σπίτι μου = my house

This is completely normal Greek word order. English puts my before the noun; Greek often puts μου after it.

They are both in the present tense:

• τηλεφωνώ = I call / I am calling
• γυρίζω = I return / I am returning / I come back

In this sentence, the present tense is being used for a habitual action:

• Τηλεφωνώ στη μαμά μου όταν γυρίζω σπίτι.
• I call my mom when I get home / when I come home.

So the idea is not necessarily right now, but this is what I usually do.

Because Greek often uses the present tense for general truths, habits, and repeated situations.

So this sentence most naturally means:

• Whenever I get home, I call my mom
• I call my mom when I get home

If you wanted a one-time future meaning, Greek would usually change the forms:

• Θα τηλεφωνήσω στη μαμά μου όταν γυρίσω σπίτι.
• I’ll call my mom when I get home.

So:

• τηλεφωνώ / γυρίζω = habitual or general
• θα τηλεφωνήσω / γυρίσω = one future occasion

Greek often omits the article in expressions involving home.

So:

• γυρίζω σπίτι = I go back home / I return home
• πάω σπίτι = I go home
• είμαι σπίτι = I’m at home

This is very natural and idiomatic.

You can also say στο σπίτι, but that feels more like to the house / to the home as a specific place.
So:

• γυρίζω σπίτι = the normal idiomatic return home
• γυρίζω στο σπίτι = also possible, but slightly more explicit/place-focused

Όταν means when.

It introduces a time clause:

• όταν γυρίζω σπίτι = when I return home / when I get home

So the full sentence has two parts:

• Τηλεφωνώ στη μαμά μου = I call my mom
• όταν γυρίζω σπίτι = when I get home

Yes. Greek word order is more flexible than English.

You can also say:

• Όταν γυρίζω σπίτι, τηλεφωνώ στη μαμά μου.

This means the same thing: When I get home, I call my mom.

The original version starts with the main action first:

• Τηλεφωνώ στη μαμά μου όταν γυρίζω σπίτι.

Both are natural.

No. Another very common expression is:

• παίρνω τηλέφωνο

So you could also say:

• Παίρνω τηλέφωνο τη μαμά μου όταν γυρίζω σπίτι.

This also means I call my mom when I get home.

A small difference in structure:

• τηλεφωνώ στη μαμά μου = verb + σε
• παίρνω τηλέφωνο τη μαμά μου = direct object without σε

Both are common in everyday Greek.

Both can mean return / come back, but γυρίζω is usually more common and more everyday.

• γυρίζω σπίτι = very natural in conversation
• επιστρέφω σπίτι = also correct, but a bit more formal or neutral

So in this sentence, γυρίζω σπίτι sounds very natural and conversational.

A simple pronunciation guide would be:

tee-leh-FO-no stee ma-MA moo O-tan yee-REE-zo SPÍ-ti

A few helpful points:

• τηλεφωνώ has stress on the last syllable: -νώ
• μαμά has stress on the last syllable
• γυρίζω has stress on ρί
• σπίτι has stress on σπί

Also, στη is pronounced like stee.

Greek does have ways to express possession, but in everyday phrases like this it usually uses weak possessive pronouns after the noun:

• μου = my
• σου = your
• του / της = his / her
• μας = our
• σας = your
• τους = their

Examples:

• η μαμά μου = my mom
• το σπίτι σου = your house
• ο αδερφός της = her brother

So μου really is the normal Greek way to say my here.

It can mean either, depending on context.

In Modern Greek, the simple present often covers both meanings:

• I call
• I am calling

In this sentence, because of όταν γυρίζω σπίτι, the habitual meaning is more natural:

• I call my mom when I get home

If the context were different, τηλεφωνώ could also mean I’m calling.

Yes, many Greek speakers would naturally use μαμά when talking about their own mother, even as adults.

So:

• στη μαμά μου = very natural, personal, everyday
• στη μητέρα μου = to my mother, more formal

Both are correct, but μαμά sounds warmer and more conversational.