English Dave said:
There is no 'proper way'. There is what works and intrigues and what sells. That has a lot to do with clarity. Make your intentions clear.
This is true, no "proper" way. The "proper" way is what works in your script.
However, I would not recommend a "start" and "stop" direction.
First, decide if the call really needs to be intercut; some do, some don't, depends kinda on their length and/or what's going on.
Sometimes an intercut will be done just to show a reaction, as opposed to letting the audience see someone speak.
For the most part, intercutting phone cons is done by the film's editor, who has done it a thousand times and learned what directors like and don't like. The director sees this in a rough cut and gives the nod or asks that it be done differently, or he or she happens to be in the editing bay when the work is done and gives the editor an idea of what they want.
A director may decide on the set the phone con won't be intercut and just shoot one end of it. If he or she wants the thing to be intercut, he'll send his AD off to shoot both ends ... in full ... so the editor has everything they need to cut the thing together at whatever points they choose.
What I've taken to doing is leaving out any indication of intercutting at all and just put one character on the screen, indicating "(VO") for the other character. This keeps the read clean. Everybody knows it will be handled by the editor or the director on the set anyway. The character on the screen should be the more important of the two, generally.
I just finished a script that had a ton of phone cons in it, all or almost all very short one, two or three speech scenes. I wrote them all in the above indicated fashion, one character on the screen, the other's speech(es) appended "(VO)".
Now, if I were faced with a longer phone con, say six or eight or ten speeches, and thought it of importance to see both characters back-and-forth, I'd do it like this:
Joe watches an NFL game on the tube. His phone rings. He has it.
JOE
Hey, Joe here, whassup?
INTERCUT
OTHER CHARACTER
Did you hear Angie got shot?
JOE
Holy crap! No! Is she alright?
OTHER CHARACTER
Only if you think dead is "alright."
JOE
Holy mother! You're serious?
OTHER CHARACTER
Totally. It happened down
at Rudolph's about an hour ago.
Some kinda fight erupted --
JOE
This's not good. She had
the money!
OTHER CHARACTER
She did? Why didja do
a fool thing like that?
JOE
Wasn't the first time.
OTHER CHARACTER
You're an idiot. Now the cops
got the money!
JOE
Tell me about it.
OTHER CHARACTER
Whatta we gonna do?
JOE
I have no idea. I'll call ya later.
Joe rings off.
Now disconsolate and shaken, he quickly rises, EXITS.
Minimal direction.
But there's lots of ways to skin this cat.
I also think "(INTO PHONE)" is redundant. To start a phone con a phone has to ring and some has to answer it. Once you indicate this, no more need be said about it, seems to me. I might elect to use it if it wasn't otherwise patently obvious the character was speaking into their phone.
But even then, I might do it like this:
CHARACTER
(into phone)
Yeah? What? Screw you, Jack!
so as to lower the profile and be less disruptive to the read.
We all have to pick our poison, eh?
Cheers!