Since you can't go out and buy a dog and a cell phone real fast.....
Of your two phone options, if you are wanting to keep him in place, try the downstairs phone. I don't know who are or what you are so... generally speaking, I would say definitely don't try to restrain him unless you know what you are doing . You probably don't have any flex cuffs or handcuffs, right?
One other thing you might consider, to ID him, have him take his wallet or ID out if he is stupid enough to carry one. Of course , you are yelling and screaming at him to do so. That way when he runs and gets away, you may still be able to ID him.
I would also guess that he would meekly lie down and be quiet until having an opportunity to escape. I can't see someone lying down on the floor and threathening someone. They will usually do it to your face to get you to back off or back down. Also don't get into a conversation with him.
I have had a couple of students who have been disarmed by burglars in their own home when were reluctant to control the burglar or shoot as the burglar closed to contact range on them. One student was severely beaten , the other ,lucky for him, was holding an unloaded shotgun on the attacker. The attacker grabbed the gun, pulled the trigger, click, then proceeded to beat the hell out of him. My student still cries about it when he tells the story. Can't say that I blame him.
Odds are, in your scenario, badguy's going to have a chance at running unless you can scare him enough to lay in place while you call the PO-lice.
Try the kitchen phone, 911, handgun at high ready,keep your front sight on him at all times !!! Hope for the best , train for the worst.
Also another safer, better option would be to call the police from the kitchen as soon as you recognize a breakin has occured rather than attempting to "clear" the house yourself.
J