The Last Phone?

         Staring at the pipe wasn't helping. If she focused hard enough, she could see the battered metal was shedding rust as red as the sunlight it tumbled through, before silently adding to the crap blanketing the ground.
         Rust, yes. Water, no.
         "Damn... hey, the shower needs unclogging again!" She paused to shake black droplets out of her fur; they had been her only reward for thirty minutes of struggling with the ramshackle plumbing.
         She had only given up for a few seconds, however, before she heard the noise.
         Taking no chances, she stretched out her hand towards the makeshift blade adorning her wall. With a pop the weapon imploded; as it collapsed into nothingness, the same crude blade simultaneously unfolded out of thin air to appear clasped in her shaking fist. Her claws tapped across the dirt as she delicately approached the hole in her wall that acted as a door.
         The mysterious noise grew louder as she got closer. It seemed familiar for some reason, although she could not identify what it was. The sound was a repeating series of shrill whistles, rather like a bizarre chorus of birds.
         "What on Earth are birds doing around here?" she muttered, dropping her guard. "I thought they only survived in Britain. They can't possibly have crossed back to the continent so soon."
         Now more curious than cautious, she lowered her blade and peeked outside.
         The noise was emanating from a small cardboard box, bleached by exposure to the bloodshot sky but otherwise intact. More than that, it was taped shut, protecting the source of the unusual sounds within.
         "Oh, it's ringing again!" The sudden shout from around the corner made her jump a mile. When she saw who had spoken, she allowed her straining knuckles to relax and let her weapon clatter to the ground.
         "What's your problem William? Do you think it's funny to scare me like that?"
         "What? Scare you? You?"
         "... More like startled, but anyway, could you tell me what this is? I was about to teleport it into the skyscraper over there in case it was some sort of Roam trickery." She pointed at the skyscraper in question. The shattered hulk lay like a felled tree, two miles distant.
         "Oh come on Sable, you can't even probamance your knife off your wall, how could you send this box all the way over there?"
         "Hey, I'll have you know I just did exactly that!" For emphasis, the blade was once again sucked into nonexistence before unfolding itself in her hand. William recoiled in mock amazement.
         "Well aren't you top shit? Hell, you can go and take on the Roam all by yourself now, we don't need to worry about them ever again!" He leant back reflexively when Sable twisted her weapon to point at him.
         "Don't joke, you know the Roam are making forays into Camp territory more and more frequently. We need to be more vigilant than ever, and every little helps." She rolled her eyes as William flicked his wrist, teleporting the noisy box into his hand. "We can't all be expert probamancers like you."
         "Don't sweat, you're not bad for a... uh..." His foot may not have literally been in his mouth but it sure felt like it was.
         "For a what?" Sable crossed her arms in front of her chest fluff. "A compound soul?"
         "I wasn't going to say that."
         "Right." She tapped her knife against her shoulder in irritation.
         "Sable, please, you know I didn't mean it like that. It's just... well, it's a fact that those of us who were purely human in the Before Years are inherently better at probamancing now. You're actually doing really well." William's eye twitched as Sable kept up her accusing glower. "Seriously." He relaxed when she waved her arm to drop the subject, scratching an itch on her muzzle at the same time.
         "Just tell me what's in the box. Shut it up too, if you don't mind." Satisfied that he wasn't about to be run through, William crossed the short distance between them and showed Sable the vibrating box on his palm.
         "It's a phone."
         "Come again?"
         "A phone. A mobile telephone." He gestured for her to slice through the tape with a claw, which she duly did. She gasped when she saw the object inside.
         "It's one of those things! It's called a foan is it?"
         "Yeah, a phone."
         "Never knew that. I mean I always used to see them around but I didn't know what they were called." Her eyes lit up as realisation dawned. "Where did you find a working foan?"
         "It was just lying around in the old capital, it had some rubble on top of it but two sides were exposed and I spotted it when I was foraging."
         "We can use this! We can communicate over long distances and organise attacks against the Roam with other Camps! This is excellent!" Her excited bouncing suddenly slowed. "Wait, we need more than one, don't we? I remember that two humans would each need one of these to talk to each other."
         "If we found one, I'm sure we can find another." William closed the box again. "You do of course realise that this little thing has greater implications than that, right?"
         "Like?"
         "Well, the fact it's ringing means someone knows how to make use of it even though the networks went down along with the rest of civilisation."
         "Oh right... what if the Roam get a hold of foans?"
         "Well that leads me to my second question..." William gazed at the box in his hand as it finally fell silent.
         "What?"
         "Like you said, you need two phones to have a conversation. So... who's calling this one?"