Is it

Cortana (Windows assistant similar to siri)

Call on me, I answer you.

I am a ring but I'm not for you.

Graphics is a ring

I can talk, I think it's surprising too!

Sort of (not really) new tech some people may be suprised by their phone talking to them

You see me away from apples

Not found on apple

Stuck on windows

Only on windows

My games are right up my sleeve

Ask her to start a game and she can (I assume)

But sometimes every now and then, your anger will want me to leave

Those voice assistants often drive me nuts

I have a sister She is older than me

Probably sister siri who has been around longer

She doesn't have time to give opinions about me,

Not confirmed but I wouldn't be suprised if Siri is designed to not talk about Cortana

But I think we're both trying to make the world better.

Both trying to improve user experience

My voice is soothing I'm a perfect lullaby singer But not only that but I can sing nursery songs, too! I have tons of them, right in here!

Probably has built ins to sing songs

July is my boss's dreams

Is it

Cortana (Windows assistant similar to siri)

Call on me, I answer you.

You can say "Hey Cortana" and it answers you.

I am a ring but I'm not for you.

That's Cortana's logo.

I can talk, I think it's surprising too!

Sort of (not really) new tech some people may be suprised by their phone talking to them

You see me away from apples

Not found on apple

Stuck on windows

Only on windows

My games are right up my sleeve

Cortana has "Guess the Horror movie" game and such games if you ask her to start one.

But sometimes every now and then, your anger will want me to leave

Those voice assistants often drive me nuts

I have a sister She is older than me

Probably sister siri who has been around longer

She doesn't have time to give opinions about me,

Siri says "No comment" when you ask her about Cortana.

But I think we're both trying to make the world better.

When you ask Cortana if she likes Siri, she says "Of course, we're both trying to make the world a better place.

My voice is soothing I'm a perfect lullaby singer But not only that but I can sing nursery songs, too! I have tons of them, right in here!

You can ask Cortana to sing

July is my boss's dreams:

July is Windows' (In this case, Bill Gates') special release month.

The hint:

As you know, Bill Gates made Windows, the OS that has Cortana, so "Open up the gates" is a key.

Is it

Cortana (Windows assistant similar to siri)

Call on me, I answer you.

I am a ring but I'm not for you.

Graphics is a ring

I can talk, I think it's surprising too!

Sort of (not really) new tech some people may be suprised by their phone talking to them

You see me away from apples

Not found on apple

Stuck on windows

Only on windows

My games are right up my sleeve

Ask her to start a game and she can (I assume)

But sometimes every now and then, your anger will want me to leave

Those voice assistants often drive me nuts

Is it

Cortana (Windows assistant similar to siri)

Call on me, I answer you.

I am a ring but I'm not for you.

Graphics is a ring

I can talk, I think it's surprising too!

Sort of (not really) new tech some people may be suprised by their phone talking to them

You see me away from apples

Not found on apple

Stuck on windows

Only on windows

My games are right up my sleeve

Ask her to start a game and she can (I assume)

But sometimes every now and then, your anger will want me to leave

Those voice assistants often drive me nuts

I have a sister She is older than me

Probably sister siri who has been around longer

She doesn't have time to give opinions about me,

Not confirmed but I wouldn't be suprised if Siri is designed to not talk about Cortana

But I think we're both trying to make the world better.

Both trying to improve user experience

My voice is soothing I'm a perfect lullaby singer But not only that but I can sing nursery songs, too! I have tons of them, right in here!

Probably has built ins to sing songs

July is my boss's dreams