The Polycom CX700 phone ships with version 7577.4100 of the Lync Phone Edition operating system. It’s an older version, from OCS days.

You can still use this phone with Lync Server 2010 and 2013, by installing the latest version of Lync Phone Edition.

However, attempting to upgrade it via the direct route fails. Turns out there’s an error in its upgrade path.

We encountered this error, and after some online research plus talking to Microsoft, came to the solution. Here it is, for your future reference!

The Problem: CX700 Won’t Allow Upgrades OR Login

Like all Polycom phones, the CX700’s OS is upgradeable. We found out about the latest version of Lync Phone Edition, Cumulative Update 7 (CU7). Hey, new version! Let’s upgrade!

Except we couldn’t. We tried logging into the phone for upgrading…and failed. The phone stalled, eventually giving us a Certificate Authentication Error.

Why would the phone resist upgrading? Were we missing a setting? Did we have the wrong process?

Time to find out. To the Internet!

The Solution: CX700 Requires CU5 Before CU7

Thanks to a call to Microsoft and one of Jeff Schertz’s excellent blog posts, we discovered the problem. It’s an error between version upgrades of Lync Phone Edition. Microsoft has not listed this error on their websites, but they will confirm the error exists if asked.

In order to upgrade to CU7, you must first install a prior update, Cumulative Update (CU5). Once CU5 is installed, the CX700 will recognize CU7 as a valid upgrade path for its OS, and the install will go through.

Jeff Schertz, a Lync Server MVP and blogger at http://Blog.Schertz.Name, has posted an explanation and workaround for the CU5-to-CU7 upgrade issue:
Lync Phone Edition CU6 Upgrade Issues – Jeff Schertz’s Blog

(His post discusses upgrading to CU6. The same process can be used for CU7.)

You must manually install CU5 to the phone, and verify its certificate, before attempting to install CU7. The steps for doing are listed in “Workaround” on the above-linked blog post.

(Using this process, you can even skip upgrading to CU6 and use CU7 instead.)

CU5 Not Available for Download at Microsoft; Download the Update File Below

Lync Phone Edition CU7 is available from Microsoft Support. However, Microsoft does not have CU5 posted on their Downloads site anymore! If you search for it, you will find a CU5 KB page. But clicking Download will give you a copy of CU7 instead.

Unfortunately, this is standard Microsoft practice. But it leaves all of us in the lurch on these phones!

Jeff Schertz again came to the rescue. He posted the CU5 download file (in .cab format) on his blog. In order to continue the goodwill, we’re offering the same file for download here:


So there you have it. Download Lync Phone Edition CU5, install it on your CX700s following the Schertz procedure, and THEN you can upgrade the phones to CU7. It’s a workaround, yes. But for now, it does accomplish the goal.

Have you upgraded your Lync-enabled phones? How’d it go?

Upgrading the Polycom CX700 Phone to Lync Phone Edition CU7

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