The first time the phone rings, the Doctor is standing in the midst of the royal court of Ambrose III, where there's a bit of a tangle involving the succession.
And he's trying to help them iron it out, he really is, but not even he can keep all their conflicting genealogies straight, and besides that, they're due for a constitutional monarchy in another fifty years, and he's facing considerable temptation to advance their timeline in favor of democratic rule by a few decades. What's half a century, after all, in the grand scheme of things?
But then he feels the phone ringing in the breast pocket of coat, snug against his left heart, and he doesn't feel any guilt at all about wandering unceremoniously out of the (putative) royal presence and into the corridor to take the call. After all, considering how causality tends to work, he was probably fated to exit negotiations at this point. Wonderful thing, free will.
The Doctor snaps the phone open with a flick of his wrist and holds it to his ear.
"Where and when?" he says into the speaker.
"Where and when are you? I can be there in less than a minute, but I need precise coordinates."
"Who is this?"
"What do you mean, who is this? Who are you?"
"Laetitia Jones, and in about thirty seconds I'm going to call the phone company and tell them my sister's mobile has been stolen."
"Tish! Nononononono, don't do that, it's me! It's the Doctor."
"Oh. Doctor... What, is Martha with you?"
"No, she's with you. On Earth, I mean, she just gave me her mobile."
"Oh...well, I hope you're giving her back part of the cost, if you're using her mobile to make calls from the Horsehead Nebula or wherever."
"You there, Doctor?"
"Yeah, yeah, sorry. Listen, everything all right? You and your mum and your dad and---everyone?"
"Yeah, we're fine. Been a strange few weeks, coming back here, after...you know, last year. We're getting on, though."
"Few weeks. That all?"
"Yeah, about. Oh, Martha had a bit of trouble with her flat. Apparently you were meant to bring her back in time to pay the rent, and never did."
"But then it turned out the flat had been blown up, so that was all right."
"...right, yes. Sorry about that. Tell her sorry for me. It's sorted now, isn't it, she isn't homeless on the streets of London or anything?"
"Yeah, she's got a new place. It's cute, you should come round and see it. Why don't you call her there? She's got a land line, you know, I could give you the new number."
"Got to go, I'm afraid, Tish. You take care of yourself."
"Oh. Right. You too, Doctor."
The next time the phone rings, he thinks to ask before initiating a conversation in medias res.
"...yes, I'm calling for Martha Jones. Who is this, please?"
"...it's the Doctor, Francine. How are you?"
"Doctor. Yes, I'm very well, thank you. Is..."
"Is Martha there with you?"
"I see. Left her mobile behind, did she?"
"Sort of, yeah."
"You should have seen her bedroom after she left home for university. I think she still has a few boxes here...Doctor?"
"Yes, right, sorry. Well, hate to cut it short, but I'm right in the middle of a collapsing supernova, actually."
"Of course. Well, it was nice talking to you again."
"You too, Francine."
"Martha's doing very well, since you didn't ask."
"Is she? Good, good, that's excellent..."
"Met a very nice young man. A doctor, actually."
"...fantastic. Glad to hear it."
"She speaks of you often, of course, but all in all I think she's moving on with her life rather nicely."
"Well, goodbye, Doctor."
The third time the phone rings, he makes no assumptions at all.
"Who is this, please?"
"This is the Doctor."
"Right, naturally, but which one?"
"What d'you mean, which one? Who's this?"
"My name is Dr Thomas Milligan. I received a call from this number recently, and I---hello? Hello?"
When the phone rings for the fourth time, he doesn't bother answering it at all. He leaves it on the TARDIS console and wanders off for an hour or so, before his curiosity gets the better of him and he checks the voice mail.
"Hi, this is Martha Jones," it says, and he catches his breath for just an instant. "I can't get to the mobile right now, but leave a message and I'll call you back soon as I can. Have a great day!"
"Martha, it's Vicky. God, you're never there, are you? Well, listen, I just wanted to tell you---Sean called me today, and we're going for coffee later---call me tonight so I can tell you about it, I'm exploding."
"Martha, there you are! About time!"
"Hi, Vicky. Martha's not here, actually. I'm a friend of hers, I'm called the Doctor."
"I---oh. Why are you calling? Is she all right? Wait, did you say you were her doctor? Oh God, is she sick?"
"No! No, Martha's fine. I'm just calling because I wanted to tell you..."
"...yeah? Tell me what?"
"This bloke, Sean. He's not worth your time."
"What? What are you talking about? Who are you again?"
"Thing is, Vicky, you shouldn't waste any more of your life on someone who needs a swift kick up the arse before he pays proper attention to you. Because it's possible, you know, that he always noticed you, that he always knew you were a brilliant, lovely, brave, magnificent sort of girl. It's even possible that he fancied the pants off you, but he didn't say anything about it, because he knew you'd be better off without him. Maybe he had some kind of dark secret in his past, or maybe his head was all twisted up with nasty ideas and memories that had no business coming anywhere near the mere idea of you. But then one day he's sitting about, and he's lonely and miserable and he starts to think, I'll ring---Vicky, because she's lovely and brave and magnificent and everything was better and brighter when she was around. Who cares if I'm being selfish, or if she's better off without me? I need her. So you have a coffee with him, and the next thing you know he's left you stranded and alone on the surface of a planet at war and you spend a year of your life fighting tooth and nail just to survive, and the thing is, Vicky, he's just not worth it."
"I'm...going to hang up now."
"Right. Sorry. My best to Sean."
The fifth time the phone rings, he fights to contain a snarl.
"Martha's not here."
"...No, I'm not there, I'm here."
"Doctor. God, it's good to hear your voice. How are you?"
"Fine! Fine, grand. Listen, now's not really a good time..."
"You're in a time machine, Doctor, go forwards or backwards until it is a good time. I haven't talked to you in months. Or, months for me anyway, may have been a few millenia for you."
"No, couple of months for me as well. It's the mobile, see. It anchors you to my personal timeline. I could travel a million years into the future, but you'd still be calling me exactly four months, twenty-eight days, and sixteen hours after you gave me the phone."
"What, no minutes and seconds?"
"Well, I haven't really been paying that close attention. So, how are things? Good? You sound good."
"Yeah, I'm---you know. Bit weird. Head all full of the year that never was."
"No doubt. You've got your family, though, you can talk to them, right?"
"Not really. They don't like to remember, more than they have to. Can't blame them, really. But I've got Jack, you know. And I'm a qualified doctor now---passed well in my exams, had a year of field experience over everyone else in my class."
"Talk to Jack, do you?"
"Of course I talk to Jack, he's here, isn't he? Anyway, that's why I called you."
"...you called me because of Jack."
"Yeah, something Jack told me. You remember when we first met, at the hospital, with the Judoon?"
"'Course I remember. How could I not remember, I'm not senile, even if I did spend a year all bald and wrinkly. Been bald and wrinkly before---well, wrinkly, anyway, and partly bald, but I had a cap, and anyway, it didn't make me forgetful. Besides, it never happened, so it doesn't count, does it?"
"Doctor, be quiet."
"Yeah. Sorry. You were saying about the Judoon?"
"They gave me something. After your---you know, genetic transfer. They had to do some kind of extended scan to make sure I was really human, and afterwards the chief rhino guy gave me some kind of weird plastic disc thingy, and when I asked what it was, they said it was 'compensation.' So I showed it to Jack, and he ran some tests on it, and found out it was like two free passes to some sort of alien resort world."
"Sorry. Thing is, Martha, I can't let Jack wander time and space with a functioning vortex manipulator just because the two of you want to go on holiday. I refuse to be answerable for the consequences. And when you consider the sorts of consequences I have been willing to answer for, you can appreciate the potential trouble he could get into."
"I'm sorry, did you think I wanted to go on holiday with Jack?"
"I'd as soon go on holiday with Leo's golden retriever."
"Oh. Right. Probably...probably wise of you, really."
"Right. Thing is, I was wondering if you wanted to go. Only I'd need a lift."
"Holiday. You want us to go to an alien resort together and, what, get manicures and bikini waxes?"
"Funny! But no, I wanted us to go to an alien resort together because, according to Jack, it happens to be on a planet where ninety percent of the economy is dependent on the slave trade, only there's a revolution happening, and the resistance is in need of some serious help."
"Doctor, you there?"
She feels it before she hears it or sees it, the TARDIS materializing behind her.
And then he's there, the Doctor, in her flat, and when his eyes fall on her his smile is brighter than an exploding sun.
"Martha Jones," he says, hands deep in his pockets. "Did you say you want a revolution?"
Martha blinks at him for a second. Then she hits him.
"Ow!" he says, but the sound is muffled in her hair as his arms close around her and her feet dangle a few inches above the carpet.
"I might have got a taste for them," she admits into his shoulder.
"Tell me about it," he says, and doesn't let go, guiding her into the TARDIS with his arm around her shoulders.
The ground is solid beneath her feet, but Martha Jones is flying.