The history of Caller ID did not begin with one invention.

Long before names appeared on telephone displays, engineers were developing methods for transmitting, detecting and displaying information about the originating telephone line.

Among the important contributors to this history were Theodore Paraskevakos and Kazuo Hashimoto, whose work is frequently associated with the development of caller-identification technologies.

Another, less frequently documented chapter of this history developed in Atlanta, Georgia.

Engineer and Georgia Tech graduate Aleksander "Alek" Szlam and colleagues developed a system that used a caller's telephone number not simply as information to be displayed, but as a key for automatically retrieving information about the caller from a computer database and presenting it to the person receiving the call.

That distinction became increasingly important as telecommunications and computers began converging.

Knowing the telephone number associated with an incoming call solved one problem.

Businesses faced another.

Who is associated with that number, and what does the company already know about that customer?

Szlam's work connected these two worlds: the telephone network and the customer database.

The resulting architecture incorporated three important functions:

1. Obtain identifying information from the incoming telephone call.

2. Use that information to locate an associated customer record in a computer database.

3. Present retrieved information to the representative handling the call.

This concept would later become widely known in the contact-center industry as screen pop—automatically presenting customer information to an agent in conjunction with an incoming telephone interaction.

The strongest evidence isn't a recollection written decades later.

It is the contemporaneous patent record.

Customer Account Online Servicing System

Filed: June 16, 1987
Issued: January 10, 1989
Inventors: Aleksander Szlam, James W. Crooks Jr. and Curtis G. Marks

The patent describes a computer-based customer servicing architecture involving customer information—including customer names and telephone numbers—stored in a mainframe system and integrated with telephone-processing equipment. 

Of particular relevance to the history of caller identification are Claims 42–45, which should be reproduced or diagrammed on this page directly from the issued patent rather than characterized simply as "Alek's Caller ID patent."

That allows the reader to examine the evidence and reach a conclusion.

This is one of the strongest additions I would make to Alek's original account.

Years later, other telecommunications inventors described Szlam's work when identifying the technology that preceded their own inventions.

For example, a later patent for a unified calling-center control system characterized U.S. Patent 4,797,911 as providing a method for automatically querying a host database at the beginning of a call, thereby relieving an agent from manually obtaining preliminary caller account information. 

Other later telecommunications patents also cite U.S. Patent 4,797,911 as prior art, demonstrating that the patent became part of the technical record against which subsequent telecommunications inventions were evaluated. 

That is independent evidence of technological relevance—not simply a retrospective claim by Melita.

The significance of the architecture becomes clearer when viewed as a sequence.

Incoming telephone call

↓

Telephone-number/ANI information obtained

↓

Number used as a database key

↓

Associated customer information retrieved

↓

Information presented to the representative

That architecture moves caller information beyond merely displaying digits.

It connects telephony identity information with stored customer information.

This is the historical contribution that should be examined when evaluating Szlam's place in the evolution of caller identification, computer-telephony integration and what later became known as screen-pop technology.

Szlam's account of the discovery and development has also been documented by his alma mater, the Georgia Institute of Technology.

In a 2023 alumni profile, Georgia Tech's School of Electrical and Computer Engineering described Szlam's work developing circuitry and real-time signal-analysis software for telephone systems. The university reports that, while testing his equipment, Szlam observed modulated signals associated with an incoming telephone call and subsequently developed and patented a process using the telephone number to retrieve information about a caller and display it on an agent terminal. 

Georgia Tech subsequently invited Szlam to present an ECE seminar titled "Genesis of CallerID and Call Centers" in January 2024. 

Those are important independent institutional references and should be prominently linked from the page.

This is where I would incorporate American Express—but only to the extent we can document it independently.

Alek's draft says the technology was used in an American Express pilot around 1986–87.

That could be extremely important evidence.

But I would not yet publish it as an independently established fact based solely upon the material I've found today.

Instead, I'd write:

Melita records and Szlam's recollections identify American Express as an early enterprise deployment/pilot of the technology during the 1980s. The Melita historical project is currently assembling contemporaneous contracts, correspondence, technical documentation and customer records to document this deployment.
 

Then we go find those records.

If we can locate an American Express document, trade publication, contract, employee testimony, system specification or dated Melita document identifying the implementation, 

American Express becomes a major evidentiary anchor.

I'd do the same for every other early customer.

This is where I'd substantially change Alek's argument.

I would not say:

"Paraskevakos transmitted a number. I identified a person. Therefore I invented Caller ID."
 

That's too absolute.

Instead:

The history suggests that several distinct engineering developments ultimately converged into what consumers now broadly recognize as caller identification.
 

Those developments included:

Originating-number signaling

→ transmitting information associated with the originating telephone line.

Number display

→ presenting the originating number to the receiving party.

Database-based identity resolution

→ using that number to retrieve information associated with a person or customer.

Screen pop

→ automatically presenting the retrieved information to a representative handling the call.

Consumer name-and-number services

→ telephone-network services that ultimately brought caller-name and number information to consumer displays.

Szlam's documented contribution belongs particularly in the database identity-resolution and screen-pop portion of that evolution.

That is a far more defensible historical proposition.

Today's communications environment routinely associates telephone numbers with identities and contextual information.

Contact centers retrieve customer records when calls arrive. CRM platforms associate communications with customer histories. Mobile devices associate numbers with stored identities.

It would be historically inaccurate to claim that a single 1980s system directly invented all of these later applications.

It is nevertheless valuable to document the earlier engineering architectures that demonstrated how telephone-network information could become a bridge to computerized identity and customer information.

U.S. Patent 4,797,911 provides a contemporaneous record of one such architecture.

And that makes the work of Szlam, Crooks and Marks an important subject in the history of computer-telephony integration.

On February 13, 1996, the U.S. Patent and Trademark Office issued this Notice of Interference involving U.S. Patent No. 4,797,911, "Customer Account Online Servicing System," issued to Aleksander Szlam, James W. Crooks Jr. and Curtis G. Marks, and a patent application filed by Ronald A. Katz.

The USPTO's interference proceeding identified competing patent claims relating to an apparatus for handling customer data in connection with telephone calls.

Of particular historical interest is Count 1, reproduced on page 3 of the original document. 

The Count describes a system that receives an incoming call, obtains the caller's telephone number, and uses that telephone number to cause a computer memory to provide an operator terminal with data associated with the corresponding customer.

On page 4, the USPTO identifies the claims corresponding to this Count as Claim 42 of Szlam et al. and Claim 98 of Katz.

This document does not, by itself, establish that Aleksander Szlam was the sole inventor of everything subsequently known as "Caller ID." It does, however, provide contemporaneous federal patent-record evidence concerning the scope and significance of Claim 42 of Patent 4,797,911 in the development of computer-integrated caller identification and customer-information retrieval.

The complete original USPTO document appears below so researchers and readers can examine the primary source directly.