Attributing Value To Phone Calls: Dynamic Number Insertion Can Help

Dynamic Number Insertion (DNI) technology allows advertisers to track the specific search engine, web page or keyword that generated an inbound phone call using tracking numbers. Advertisers are using DNI to measure the performance of their online advertising campaigns and the impact on call volume. At the most basic level, DNI seamlessly replaces select contact phone numbers on a web page with call tracking numbers, which allows advertisers to measure volume. Combined with pay per click programs, DNI can help complete the online advertising performance picture by clearly outlining the results of advertising campaigns both online and by phone. Advertisers using DNI to measure and report phone calls driven by web activity use two different methods: a server-side method called reverse proxy, and a client-side method that uses Javascript tracking codes. While each approach is different, both offer advertisers unique benefits and value.

Reverse proxy method: Best suited for local advertisers

With the reverse proxy method, instead of web requests going directly to an advertiser’s website, the user request is routed to an intermediary server which determines what content should be displayed. This proxy retrieves the content from the advertiser’s website and transforms the output by inserting and/or replacing specific phone numbers on the page with call tracking numbers based on keyword or search engine triggers. This is done via cached copies of an advertiser’s website or in some cases, in real-time, for every request through the proxy so that any dynamic content included on the advertiser’s page is reflected ensuring that data is always current and up-to-date.

As reverse proxy capability is more readily available from SEM or other third party resellers, this approach is very effective for local advertisers or SMBs that do not have sophisticated internal technology resources easily available to make modifications to their existing websites. However, because a service provider is involved, it is typically more expensive. Also, reverse proxy is a better option for advertisers that use third party website functionality for shopping carts or email forms.

A disadvantage of the reverse proxy method is that it is not well suited for tracking organic search activity. Reverse proxy sites are invisible to search engine spiders, so organic searchers would never reach a reverse proxy site and online organic search activity is not captured. Also, larger advertisers with complex websites that are considering this approach should ask the reseller about their reverse proxy method as some require the advertiser to share control of the websites as they continuously make duplicate or updated copies of the page. This “carbon copy” approach would be a complication for advertiser sites that include real-time data such as news feeds, RSS or stock quotes, as it risks serving static or old data.

Javascript tracking codes: Best suited for national advertisers

In the Javascript tracking code method, user requests are routed to the advertiser’s actual website rather than through a third party intermediary. Similar to Google Analytics, a piece of Javascript code containing a unique identifier is inserted into an advertiser’s webpage which links to the SEM provider’s servers via a web service. When an ad click or organic search result routes a user to the advertiser’s website, the Javascript takes the parameters used to perform the search along with the advertiser’s unique identifier and passes them to the SEM provider to be processed against predefined keyword, ad group and browser triggers. The result is a series of phone number substitutions returned to the advertiser’s page where it is used to dynamically update the content with the designated call tracking numbers.

Since the coding is performed client-side, this method requires HTML design and maintenance expertise—something typical SMBs lack. It is best suited for larger, national advertisers with committed monetary and technology resources or which have access to specialized agency resources that can perform such maintenance.

A benefit of the Javascript tracking code method is that advertisers can use it to track organic search activity. This method uses an advertisers’ primary website and domain names, which are easily visible to search engine spiders and enable advertisers to compare the organic traffic from a keyword or ad campaign on Google versus Bing. As such, Javascript tracking code is the best method for tracking full search engine optimization and marketing results. Also, because this method uses traditional or primary domain names, such as, rather than a third-party provider URL like, national advertisers have more control over their branding standards.

One minor pitfall of this method is that some browsers disable Javascript tracking code. It is a small percentage but does represent a data loss.

The overall benefits of DNI—through either method—are simple: DNI provides advertisers greater visibility to the source of inbound calls and allows advertisers to track the performance of specific ads and/or keywords. With the ability to capture the full value of online advertising initiatives adding call counts to the traditional click count approach to online campaign performance, advertisers can optimize their spend and move underperforming keyword-search engine ad buys to more successful combinations.

Opinions expressed in the article are those of the guest author and not necessarily Search Engine Land.

Related Topics: Channel: SEM | How To: SEM | Search Ads: Pay Per Call


About The Author: is president of Telmetrics, a provider of call measurement solutions. Dinan has led Telmetrics' evolution from print-centric tools to multi-media, leads-based measurement solutions and was appointed president in May 2009. He can be reached at

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    While I understand Bill needs to run a company and make massive profit and his post has some merit, the whole concept of DNI is faulted in the real world of advertising.

    Problem #1: You will always sell more and do better by using clear, easy to remember 1-800 numbers/local numbers. So if Bill’s company could provide perfect looking 800′s numbers each and every time that would solve this problem, but causes problem #2.

    Problem #2: Users write down, rolodex, save numbers they call and DNI systems that are managed by companies like Bill’s means your customers will be calling you but getting someone else in the future or getting sorry this number is out of service. While some of the DNI companies can offer you to use/own the numbers this creates problem #3.

    Problem #3: If you want to keep ownership & control of all these different numbers, it would be very costly. Bulk 800 numbers are not cheap, and local bulk lines also have a price. Your monthly bills for phone lines easily pill up and if you drop one line you loss the customers associated with that line. The DNI companies might be able to save some cost by helping you buy the numbers, but this problem is only solved by the proper way to handle call tracking, which is solution below:

    Having been in the business for 11+ years I’ve seen a lot of companies use the above process, always with success and failure. Sadly the failure rate/benefit is greater then the success in the above process. But there is a very clear, easy to use way to handle this, but since Bill’s company doesn’t offer it and since most of the other providers also don’t offer it you’ll only see/hear about from major/smarter advertisers.

    Solution: using a great branded/easy to remember 800/local number along with a easy to remember/branded/related extension or promo code. As this handles the tracking aspect, ensures that you don’t loss business because of a bad phone number shown, and you will loss business if you use a bad/ugly phone number. IT also ensures that you will have ownership and control of the number, costs will be low as you only run 1 number.

    The only bad thing about this is you will need to find a provider that can do it, which is the problem as at present most of the companies are looking for profits and looking out for themselves not you. So sure the solution from Bills company is a solution, but it comes with a hefty price and anyone seriously looking at call tracking should think twice.

    The only things I can offer in terms of a possible solution are: 1) have your staff that answer the phone trained to ask for a promo code or 2) use a PBX system that prompts the user to enter the promo code/extension number. Then you will still need a way to handle the rotation of the extensions based on the keywords/advertising that brings traffic, for that I have no solution and only say I wish companies like Bill’s were able to actually do what’s right for the client, even if it meant making a little less as the concept is right, the system is there, just the execution is wrong.

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