Chances are, the smartphone in your hand isn't your first. And chances are, it's carrying contacts from three, five, even 10 years ago that you've been faithfully migrating from phone to phone.

My iPhone address book holds nearly 800 contacts including defunct numbers, contacts containing no information, and of course the requisite dozens of duplicate contacts. This is the result of years of syncing various email accounts and social media profiles. Blank contacts can be created when Android phones use Google Voice to message or call contacts. Allowing Facebook to sync contacts with your phone book way back when could have added tons of not-really-friends into your phone.

  Until recently, I just ignored the growing chaos of my contacts list. If I needed to call someone who wasn't already in my favorites, I typed their name into the search box and never, ever tried scrolling.

But your contacts list isn't just for making calls. It also populates messaging apps like WhatsApp, Snapchat and Viber. It powers your email contacts, and it rears its head in your calendar app too.

It's worth your while to clear the clutter in your contacts list and, at the same time, streamline your other accounts.

1. Get unsocial

If your contacts list is crawling with unwanted Facebook contacts whose birthday reminders are now firmly lodged in your calendar:

iPhone: Settings > Facebook > Allow these apps to use your account, then slide the tab to Off for Contacts. To prevent Facebook event invitations from turning up in your calendar, slide the tab to Off for Calendar too.

Android: Settings > Account & Sync > Facebook, and uncheck Sync Contacts.

Windows Phone: Settings > Applications > People > Filter Contact List.

Follow these steps to unsync contacts from other social apps such as LinkedIn and Twitter.

2. Zap random email address-only contacts (Android only)

If you're a Gmail user with an Android phone, you may have noticed contact entries that contain only email addresses. That’s because Gmail has a feature that automatically adds new people you email to Other Contacts (or Ungrouped Contacts) in your contacts list. The feature’s handy when it comes to auto-completing email sender fields but irritating when it comes to creating a phone book full of random addresses, from emails to webmasters or customer service accounts.  

While the Gmail app for iPhone and Windows Phone doesn't sync to this folder, relieving iOS and Windows Phone users of the issue, Android users might find they've unknowingly synced their phonebook to these contacts. To disable it, head to your contacts app and tap Phonebook, then the settings for Google and uncheck the box for Other Contacts as a contacts source.

3. Merge duplicates and multiple entries

One of my friends is in my contacts list five times, with separate entries for his email address, his old email address, his Facebook profile and two phone numbers. You can merge cloned pals like this by manually opening each contact card, but if you have several to merge — and like mice, if you've got one, you've probably got a dozen — this process will be painstaking.  

Instead, download a duplicate-killing, clone-merging contact cleaner app (unless you're on Windows Phone; see below).

iPhone: Check out the free Cleanup Duplicate Contacts, which scans your phone and presents you with a list of partial and total dupes. You then review the list and hit Merge to zap the doubles.

Android: Newer phones, including the Samsung Galaxy S8 and HTC U11, contain features within the Phone app for removing duplicates and merging linked contacts. If your phone doesn't, try Contacts Phone Dialer: drupe, a free contacts app that will analyze your address book for duplicate contacts.

Windows Phone: Go to outlook.com, log in with the email address associated with your phone and select Settings > People > Manage > Clear Contacts to automatically scan your contacts and view a list of all duplicates. You’ll be given the option to merge them.

Cleaning up duplicates is a good temporary measure, but dupes and extras will crop up again if you have enabled contact syncing for more than one account such as iCloud, Gmail and Hotmail. To minimize upkeep, create a single, cloud-based address book.

4. Create a single, cloud-based address book

Pick the email service you use the most as the destination for backing up your address book. I have both Gmail and Outlook.com accounts, but Gmail is my primary email. So that's where I'll create my consolidated address book, including Gmail contacts, phone contacts and backups of my contacts from Outlook.com and iCloud.

Export the contacts from any other services you use as a CSV file or vCard file. For email accounts, Microsoft Exchange or iCloud, head to the relevant website and to the contacts section to manage contacts, including exporting. If you have contacts that are saved only on your phone, Android users can do this from the contacts app; iPhone users must download an app such as My Contacts Backup for exporting contacts as CSV and vCard files. Contacts saved on Windows Phone are automatically saved online, accessible by logging into windowsphone.com.

Head into the email service you've chosen as your contacts backup central, click to the contacts section and select the option to import contacts. You'll be prompted to upload the CSV or Vcard files from your other accounts, resulting in that cloud-based, universal phone book you've always wanted.

5. Polish by hand

Not every defunct contact can be mass-merged away. Go through your newly dupe-free contacts list and look for stuff that software can't spot. Delete people you don't know and numbers that you know are no longer in use, and update default numbers for calling (even your grandad probably prefers to be contacted on his cell phone instead of his landline these days).

6. Clear your phone of contacts

Now that you have a single repository containing all your cherry-picked crucial contacts, you can safely clear your phone of all its numbers —without deleting them from their online accounts — before reloading your clean, consolidated address book.

iPhone: Try Groups. It's not the best-looking app out there, but it's free and it allows you to make bulk deletions quickly.

Android: Download Contact Remover to easily delete all contacts from your phone without affecting the accounts the contacts are from.

Windows Phone: You may be out of luck here. Like iOS and Android devices, there's no in-phone ability to make bulk deletions from your phone without deleting from your Windows Phone account. The Windows Store doesn't seem to have third-party apps for doing it, either. Let us know if you find otherwise.

7. Resync your all-in-one address book

Now sign in again with your email address and check that you have enabled sync for Contacts.

iPhone: Go to Settings > Mail, Contact and Calendars > [your account].

Android: Go to Accounts & Sync [your account].

Windows Phone: Go to  People > Settings > Accounts [your account].

8. Keep it clean

With a newly spring-cleaned contacts list, you'll want to fine tune your phone settings to keep it that way. If, like me, you have an email address you use mostly for signing up for newsletters or site accounts, prevent it from syncing any contacts to your phone.

iPhone: Settings > Mail, Contact and Calendars

Android: Settings > Accounts & Sync

Windows Phone: People > Settings > Accounts, deselect Contacts to sync.

On the flip side, to ensure that new contacts you add to your non-primary email accounts are synced to your phone, check the above settings to ensure that you've enabled contact sync for those accounts.

When saving a new number to your phone, check that the contact type is set for the account you've designated your contacts hub —in my case, I'd save a new number to Google, not my SIM card or the phone — so that new contacts are added to your cloud-based universal phonebook, keeping it up to date.

iPhone: Settings > Mail, Contact and Calendars > Contacts > Default Account

Android and Windows Phone: Choose the Contact Type (Android) or Account (Windows Phone).