What Is a Microsoft Confirmation ID (CID) and How Do You Get One?

What a Confirmation ID (CID) Actually Is

A Confirmation ID (CID) is a short numeric code Microsoft's activation servers generate in response to your Installation ID — the code your copy of Windows or Office shows you when it can't activate automatically over the internet. Entering the CID back into the activation wizard completes the process manually, the same way an automatic online activation would have.

It isn't a workaround or a trick — it's Microsoft's own built-in fallback for exactly this situation, and it exists precisely because automatic activation doesn't always succeed on the first try.

When You'll Be Asked for One

1. Automatic activation failed or is blocked — a firewall, proxy, or network policy is preventing your PC from reaching Microsoft's activation servers directly.
2. You're activating over the phone — the "Activate by phone" option in the activation wizard always uses this Installation ID → Confirmation ID exchange, whether you call an automated line or read the numbers back manually.
3. Volume/MAK license activation — some volume-licensed copies of Windows or Office are specifically configured to activate this way.
4. No internet access on the machine — if the PC being activated genuinely has no network connection, phone activation with a CID is the only path available.

How the Installation ID → Confirmation ID Exchange Works

1. Start activation on the machine and choose Activate by phone (or "I don't have an internet connection" on some Windows/Office versions).
2. The wizard displays your Installation ID — a long number, usually shown in groups of digits.
3. That Installation ID gets submitted (by an automated system, or read aloud on a phone call) to Microsoft's activation service.
4. Microsoft's system returns a Confirmation ID matched to that exact Installation ID.
5. You enter the Confirmation ID back into the activation wizard on your PC, and activation completes immediately.

For the full click-by-click walkthrough with screenshots on each version, see our step-by-step guides: How to Activate Windows by Phone and How to Activate Office by Phone.

Common CID Problems

1. "This Confirmation ID isn't valid" — the ID is tied to one specific Installation ID. If you re-ran the activation wizard and got a new Installation ID, any previously-generated CID no longer matches it.
2. Digit groups don't line up — double-check you're entering the CID into the matching numbered boxes in the wizard; a single misplaced group is the most common cause of a rejected code.
3. The automated phone line doesn't recognize your Installation ID — this usually means the wrong country/region was selected for the automated system, or the product key type doesn't support phone activation at all.