In the traditional telephony context, third party call control allows one entity (which we call the controller) to set up and manage a communications relationship or telephone call between two or more other parties. Third party call control (referred to as 3pcc) is often used for operator services (where an operator creates a call that connects two participants together) and conferencing.
Similarly, many SIP services are possible through third party call control. These include the traditional ones on the PSTN, but also new ones such as click-to-dial. Click-to-dial allows a user to click on a web page to speak to a customer service representative. The web server then creates a call between the user and a customer service representative. The call can be between two phones, a phone and an IP host, or two IP hosts.
Third party call control is possible using only the mechanisms specified within RFC 3725[1]. Indeed, many different call flows are possible, each of which will work with SIP compliant user agents. However, there are benefits and drawbacks to each of these flows. The usage of third party call control also becomes more complex when aspects of the call utilize SIP extensions or optional features of SIP. In particular, the usage of RFC 3312 [2] (used for coupling of signaling to resource reservation) with third party call control is non-trivial, and is discussed in Section 9 of RFC 3725 [3]. Similarly, the usage of early media (where session data is exchanged before the call is accepted) with third party call control is not trivial; both of them specify the way in which user agents generate and respond to SDP, and it is not clear how to do both at the same time. This is discussed further in Section 8.
Yo 'Pac yo, I heard you got beat up by the police
Got a big fat lawsuit and everything
Niggaz just wanna know
if you still gon' be on some crooked-ass sheeeit
[2Pac]
Please tell me what's a nigga to do, and it's true
Ain't nuttin new, so I do, what I can to get through
Now first they had me trapped and now I'm pissed
A loaded AK-47 lay under my head so I don't trip
One motherfucker from the Underground
And Big Stretch buckin niggaz if they fuck around
Yo why I got beef with police?
Ain't that a bitch that motherfuckers got a beef with me
They make it hard for me to sleep
I wake up at the slightest peep, and my sheets are 3 feet deep
I guess it's hard for you to see
But now I'm pointin the finger at police
instead of them motherfuckers blamin me
I got the right to bear a pistol
And when the punk motherfuckers get to trippin I got shit too
And maybe then you'll see the truth (hell yeah)
But until then, I gotta do what I do
and stay a crooked nigga too
[Chorus: Raphael Saadiq]
I've got to do, what I'm gon' do
I'm gon' say what I'm gon' say
I'm gon' live how I live - how else you want a nigga to live?
I'm gon' do, what I do
I'm gon' say, what I say
I'm gon' live how I live - how do you want a nigga to live?
[2Pac]
Y'know you really can't say that ya blame niggaz
Fuck bein tame, set aflame, time to aim triggers
2Pac'll spark a revolution, fuck the Constitution
I want my bucks for restitution
This time you got a bigger problem
Time to face the niggaz from South Central, Oakland, Brooklyn and Harlem
And we ain't shootin at each other
That's my motherfuckin brother, so Dave Duke, run for cover
And all the bitches from the Klan
Come feel the wrath of a black man that doesn't smoke crack and
I don't drink St. Ides (fuck that!)
Genuine Draft, ganja ganja, and my fuckin tec-9
They know they scared to see us sober
Stop drinkin King Cobra, and niggaz'll take the world over
It's all up to you (up to you)
Blame the Korean, blame the jew, or be a crooked nigga too
[Chorus]
[2Pac]
Aiyyo! Why me? Play like Jasmine Guy and try me
I'll be damned if I die, come look at the rage in my eyes G
They got my homies in a jail cell
And it's the Rebel and the Devil, and one of us is goin to Hell
I got the whole place covered, with loc'd out brothers
And nuttin but love for each other
So motherfucker make a motion
I give a fuck, slice you up, and throw your ass in the ocean
Temperatures drop; see it's cool to shoot a nigga
but they hate it when we pop the cops
That's when they gettin petrol
You better watch your step or you'll be left on death row
But I learn to look ahead of me
Stay strapped watch your back keep your eyes on the enemy
We blowin up precincts and OOOH
You can't fuck with the crew, of crooked nigga too
[Chorus]
[Raphael Saadiq]
It's the coldest town from here to Georgia
(I'm a crooked nigga too)
It's the coldest town from here to Georgia
It's the coldest town from here to Georgia
(I'm a crooked.. crooked nigga too)
It's the coldest town from here to Georgia
Y'all gon' stop fuckin with me
[Chorus - repeat to fade]