Quero contratar o roaming.

In Brazilian Portuguese, the subject pronoun is often omitted when the verb already makes the subject clear.

• Quero = I want
• So Quero contratar o roaming already clearly means I want to get/sign up for roaming

You can also say Eu quero contratar o roaming, but the eu is usually unnecessary unless you want emphasis or contrast.

Quero is the 1st person singular form of querer.

• querer = to want
• quero = I want

So:

• Quero contratar... = I want to get/sign up for...

It is a very common verb in everyday speech.

Contratar is very common in Brazilian Portuguese for services, plans, or subscriptions.

It can mean:

• to hire
• to contract
• to sign up for
• to purchase a service

So with phone services, contratar o roaming sounds natural because you are getting a service activated as part of a plan or package.

By contrast:

• comprar is more literally to buy
• It works better for physical things, though it can sometimes be used for services too

Here, contratar is the more idiomatic choice.

In Portuguese, nouns often appear with a definite article where English would not use one.

So:

• o roaming = literally the roaming

Even though English usually just says roaming, Portuguese commonly uses the article with this kind of service name.

Without the article, contratar roaming, it may still be understood, but contratar o roaming sounds more natural in many contexts.

Because in this sentence it takes the article o, which marks it as masculine:

• o roaming

Loanwords in Portuguese are assigned grammatical gender, and here roaming is normally treated as masculine in Brazilian Portuguese.

This does not mean the word is inherently masculine in meaning; it is just a grammar category.

Yes, roaming is widely used in Brazil, especially in telecom contexts.

You may also hear more specific expressions such as:

• roaming internacional
• serviço de roaming
• serviço de roaming internacional

In some contexts, people may talk about:

• habilitar o roaming
• ativar o roaming

But roaming itself is absolutely normal and very common.

Yes, it is natural, especially if you are talking to a phone company or customer service and you mean you want to add that service.

That said, depending on the situation, a Brazilian might also say:

• Quero ativar o roaming.
• Quero habilitar o roaming internacional.
• Quero contratar um pacote de roaming.

The nuance is:

• contratar = sign up for the service
• ativar / habilitar = turn it on or enable it

So your sentence is good when the idea is getting the service from the provider.

The structure is:

• Quero = I want
• contratar = to contract / sign up for
• o roaming = the roaming service

So the pattern is:

• [conjugated verb] + [infinitive] + [object]

This is very common in Portuguese:

• Quero comer. = I want to eat.
• Quero comprar um chip. = I want to buy a SIM card.
• Quero contratar o roaming. = I want to sign up for roaming.

A rough pronunciation guide would be:

• Quero ≈ KEH-roo or KEH-ro
• contratar ≈ kohn-trah-TAR
• o = a short oo
• roaming is a borrowed word, so pronunciation can vary, but many speakers say something close to ROH-ming or HOH-ming

A rough full version:

• KEH-ro kohn-trah-TAR oo ROH-ming

Depending on the speaker and region, the borrowed word may sound more English-like or more adapted to Portuguese pronunciation.

Yes. That sounds more polite and a bit more formal.

Compare:

• Quero contratar o roaming. = I want to sign up for roaming.
• Eu gostaria de contratar o roaming. = I would like to sign up for roaming.

Both are correct. The second is softer and often better in customer-service situations.

Often, yes.

If the context is not already clear, roaming internacional is more precise because it specifies that you mean mobile service outside Brazil.

For example:

• Quero contratar o roaming internacional.

That may sound more natural than just o roaming if you are speaking with a provider and want to avoid ambiguity.