Investigating Verizon’s Network Optimization

Earlier this year, Verizon Wireless adopted a process it calls Network Optimization with the goal of more efficiently transmitting data to its customers, and thereby reducing the load placed upon its wireless data network. It turns out that this process actually works by intercepting data sent to your phone, particularly HTTP data over port 80, and applying lossy compression before passing it along to you.

Verizon claims that the information it removes from images and videos is conservative, for example by removing only colors not visible to the human eye.

Rather than simply trust Verizon, I decided to empirically test the effects of its optimization process.

The experiment

For my experiment, I built a simple app for my iPhone 4S that would download an uncached copy of a list of URLs. The URLs I selected were all images in jpeg or png format from my own web server and a variety of well known websites, including Apple, Amazon, Google Maps, and Flickr. I ran my app once on my WiFi network at home (connected to the internet via Comcast) and then again with WiFi disabled, using Verizon’s data network.

Finally, I copied the images off my iPhone using Xcode.


Of the fourteen images I downloaded, nine had been altered by Verizon. The savings were significant: the images downloaded via WiFi totaled 2.1MB, while the same images fetched over Verizon totaled 796KB. That’s less than 50% of the original size, despite the fact that five of the images had been left untouched. Among the files left untouched was a 500x333px image from flickr and some of Google’s map tiles. Satellite tiles from Google Maps were not spared.

For the images that were modified by Verizon’s network optimization, the results were mixed. One photo of my cat showed an 80% reduction in file size with a minimal, but still discernible, effect on the quality of the image, while the quality of Atomic Object’s logo was very visibly sacrificed in the effort to bump it down from 27KB to 5.3KB. In another case, a product photo from Amazon suffered noticeably in quality for the sake of saving 2.7KB.

It’s worth noting that in all cases where Verizon applied re-compression, it also stripped out almost all image metadata.


Unlike Verizon claims, it’s clear that the loss of quality is not imperceptible, although it was very hard to tell with some images. To Verizon’s credit, the reduction in quality certainly pays off in the end with significantly less data to transfer, leading to faster load times. I believe this technique helps explain why I have observed that Verizon iPhones tend to load web pages faster than their direct AT&T counterparts, despite AT&T having a theoretically faster data network. Additionally, if Verizon is honest in their recording of data usage, it could also help you get more out of your metered data plan than you would with AT&T.

Despite the benefits, it’s still rather unnerving to know that your data is being mutated on its way to you. You might want to think twice about downloading new wallpaper over 3G. Or anything else where quality matters. But, thankfully, network optimization is only applied to HTTP traffic over port 80, so, for example, your email and encrypted web sites should be fine.

  • David Smith says:

    Thanks for doing this test. Very interesting. I’m on Chrome and the hover effect didn’t work for me.

    • Chris Farber Chris Farber says:

      Thanks, David. The hover works for me in Chrome – it’s actually just using very simple CSS and no Javascript. Look closely at the blade and logo on the knife as you hover over it, I think that’s the easiest to see.

      • David Smith says:

        Oh you are right Chris. Last night when I was looking at it I was wondering if that was going on. I tried looking really close. I guess I was tired or needed better light. Today it is more noticeable :)

  • Brian says:

    Thanks for posting this. I was wondering why the heck the photos I am viewing online look so crappy. Verizon says I am not being throttled, but it is clear (or unclear, as the case may be) that they are doing something to the images I am accessing online.

  • […] images with the ones on my hard drive and there is significant degradation in quality. I also found this post that explains exactly what I am seeing, and it is definitely a result of Verizon’s image […]

  • […] images with the ones on my hard drive and there is significant degradation in quality. I also found this post that explains exactly what I am seeing, and it is definitely a result of Verizon’s image […]

  • RPW says:


    It would have been nice if you would have elaborated on how Network Optimization impacts MiFi Users with laptops (MacBook) rather than just mobile devices (phones). This practice has frustrated me to no end and I’ve made more calls to Verizon than I care to say. It is a far bigger PROBLEM than you seem to indicate. Your test was a good start but there is much more to it that people should know. This practice is WRONG and Verizon should be sued for it.

    If it were as simple as you seemed to indicate in your article – that would not be a huge problem but it is much worse than this for customers such as myself who are tagged as “high data users”. Data Hogs! Thats about as ridiculous as ComCast telling it’s customers that they watch too much TV and are slowing down their networks, and therefore need to be “throttled” to allow other customers who don’t watch as much TV. This is a problem that people need to stand up against. We keep getting sucked for every nickel we have and there’s ALWAYS an excuse by corporate America. It’s GREED. Plain and simple!

    • Brian says:


      I am also using mine on a laptop via a USB modem. It is much, much worse than described in this post, but I was still glad to verify that I wasn’t just imagining things. I did a test today and downloaded the same image via Verizon at home and AT&T at work. Verizon compressed a 28kb image down to 6kb. I manage several websites, and I need to see what other people online are seeing in order to create and manipulate design elements.

      I suspect I have also been flagged a high data user – simply because I used more data than normal last month. The ONLY thing Verizon has going for it is coverage. They care absolutely nothing about their customers.

      • Chris Farber Chris Farber says:

        RPW, you’re right. I think this compression is simply unacceptable for real use, especially when you’re using a real computer. I find it only somewhat acceptable because I’m often (about 95% of the time) on a WiFi network that isn’t intentionally crippled.

        Brian, it’s important to note that they do this to ALL their mobile customers, not just people flagged as high data users. And, according to their TOS, Verizon only throttles speed for customers flagged as heavy data users, and even then it only does so on congested areas of the network.

  • Anthony says:

    I connect my desktop computer with 21″ monitor using Verizon’s MiFi 2200. I have noticed how bad the images are and I’ve called them 3 or 4 times now to discover what is going on. Each of their reps have played stupid, or outright denied any compression is taking place and one even suggested that the problem was with my computer. I’ve worked with Apple technical service and have done everything to ensure that it is not my computer. I can tell you that I’ve eliminated all of the proxies and such that would alter images and nothing has worked. One web page I came upon suggested that the software is loaded by Verizon onto our computers. The application is called Venturi compression. Does anyone know how to disable this software or otherwise work around the graphic compression taking place?

    • Chris Farber Chris Farber says:

      Anthony, you probably don’t actually have Venturi installed. The compression that I’ve shown in my post is actually done completely transparently to the computer. Essentially, Verizon compresses images and other types of media before they are even transmitted to you.

      Unfortunately there is nothing you can do to turn it off, short of ditching Verizon.

  • Brian says:

    I am curious if this compression will continue on devices connected to Verizon’s 4G network? My current MiFi connection is on 3G. I hope the faster network will allow them to provide the images without compression. Any thoughts?

    • Chris Farber Chris Farber says:

      I wouldn’t hold my breath for it. Compressing media will probably still make a noticeable impact on loading times, and as long as Verizon thinks (likely correctly) that their users won’t notice the difference in quality but will notice the difference in speed, they’re going to keep doing it.

      It also helps them look favorable when compared to AT&T…

  • Brian says:

    As far as I can tell, images on Flickr are NOT being optimized. I assume this is because Verizon knows it’s a website dedicated to photography. Google Photos (Picasa Web) also seems to be unaffected. I haven’t noticed any quality degradation on Google+, which pulls photos from Google Photos. Images on other websites are noticeably lower quality. Can you confirm this on your computer?

    I am using Millenicom’s internet service, but the connection is going through Verizon. I contacted them a few weeks ago when I first noticed this problem and they check with Verizon and said I wasn’t being throttled and there were no problems with my local tower. They suggested I call their support line if the problem continued. I haven’t done it yet, because I don’t feel like spending a lot of time on the phone trying to describe a problem that is beyond their control.

  • Anthony says:

    I’ve been seeking resolution (in more ways than one) by Verizon for this condition for some time now and here is an update. On Friday, they called me back to let me know that it was a local tower hardware problem. I told them that I experienced the same compression 38 miles away and he said he would check into that. Upon doing so, and in a subsequent call, he said this was a problem confined to a corridor ranging from MO to WI. Just prior to his first call, I was in the process of taking my desktop computer and my MiFi 2200 to a local Verizon store. They checked all my settings and witnessed the problem. When I connected with their wifi, I got compressed images too. They said they would file a repair order. So, as it stands, I’m waiting to hear what’s going to be done about this ‘corridor’ related problem. I’m in southeast WI. Are any of you in areas outside this corridor?

    • Brian says:

      Hi, Anthony. I am in Kentucky. I have narrowed the problem down to my local tower, but haven’t called the issue in. I get compression here on my laptop connected via a USB modem and on my phone when it is using Verizon’s 3G. Someone online suggested that I try a VPN to see if I could get around the image compression and it worked. Anytime I want to see or download a full-quality image, I just connect to the VPN.

  • Brian says:

    I found an easy workaround on my computer via a forum on DSLReports. In Chrome, I can click CTRL + F5 twice and the uncompressed image will load. In IE, CTRL + SHIFT + Refresh. See if you guys have the same results.

  • Anthony says:


    I’m glad you found a work around, even if it requires a little more “hands on” involvement than should be necessary. I’m using a Mozilla (Firefox, SeaMonkey) based browser and was not able to get any combination of modifier keys to work. That’s not to say there isn’t a combination that will work, but I’ll have to leave the experimenting for some other time. I’ll keep you posted.

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