If you work investigations, you will need to analyze call detail records. Who called or texted whom, and when. It’s one of the most basic and most vital elements in uncovering crime and finding hidden connections between perpetrators. This is the guide to that moment: what the records are, where they come from, what they contain, and what SentVi does with them that a spreadsheet cannot.
What call detail records are
Call detail records, also called call data records, CDRs, or simply phone records, are the logs a carrier keeps of activity on a phone. Every call placed or received, and every text sent or received, generates a row. The row does not contain what was said. It contains the facts around the communication: which number reached which number, when, for how long, and often where.
Carriers keep these records for billing and network management. Investigators use them because they are an objective, timestamped account of who a phone was in contact with, generated by a third party with no stake in the case.
Where they come from
In the United States, the records come from the carrier that services the number: Verizon, AT&T, and T-Mobile operate the networks, and the prepaid and discount brands (Cricket, Metro, Boost, Visible, Mint, Straight Talk, and the rest) ride on one of those three, so the records ultimately trace back to one of them.
How you get them depends on who you are:
- Law enforcement obtains them from the carrier through a subpoena, a court order, or a search warrant, depending on what is being requested and the jurisdiction. Basic subscriber and toll records are generally the easiest to obtain; historical cell-site location data typically requires a warrant.
- Litigation teams obtain them through a subpoena to the carrier, through a party’s own account records, or through production from the other side. A client can also pull their own detailed call history from the carrier’s account portal.
- Private investigators and outside investigation firms most often work with records a client already holds, or that counsel has obtained, and are frequently the ones doing the analysis for the attorney.
Every carrier returns records in its own format, with its own column names, time zone conventions, and ways of identifying cell sites. A return from AT&T does not look like a return from T-Mobile. Anyone who has worked more than one case knows that the first several hours are spent figuring out the file before any analysis starts.
What is in the file
Formats vary, but a typical return includes some or all of the following for each row:
- The originating number and the terminating number
- Date and time of the call or text, usually with a start and end or a duration in seconds
- Direction (incoming or outgoing) and type (voice, SMS, MMS, data session)
- Device identifiers such as IMEI or IMSI, which tie activity to a physical handset or SIM card rather than a number
- For cell site records, the tower and sector that handled the call at the start and end, which places the phone in a general area at that moment
A single phone over a 90-day period can easily produce several thousand rows. A tower dump, which is every phone that connected to a tower during a given time window, can produce tens of thousands of records. A case with records for five or six phones is well into six figures.
Why they are hard to work in a spreadsheet
The rows are simple. The problem is what you are actually trying to learn from them, which is almost never contained in a single row.
You want to know which numbers this phone talks to most, and whether any of those numbers also talk to each other. You want to know whether two subjects who claim not to know each other share a contact. You want to know what changed in the calling pattern after a specific date, and whether a phone was near a location at a specific hour. You want to know whether the same number appears in the records of three separate incidents.
Each of those is a question about relationships across rows and across files. In a spreadsheet, that means pivot tables, lookups across tabs, manual format normalization, and a lot of scrolling. It is doable. It is also slow, easy to get wrong, and nearly impossible to hand to someone else.
What SentVi does with call detail records
SentVi is link analysis software. Its job is to take rows and columns and turn them into a network of entities and relationships you can search, filter, and see. Call detail records are one of the datasets it was built for.
Import once, reuse forever
SentVi imports directly from Excel, CSV, and text files, Access, and SQL Server, with no record limit. The Import Wizard maps your columns to two entities and one relationship: originating number, terminating number, and the call between them, with date, time, duration, direction, and cell site carried as attributes of the call. A WHERE clause lets you import only the rows you need, and a preview shows you the first 500 rows of what will be created before you commit. A checkpoint backs up the database so a bad import can be rolled back.
The import specification is then saved. The next return from the same carrier in the same format loads in minutes, not hours. That alone changes how many phones a team can afford to analyze on a case.
The data lives in a Microsoft SQL Server database on your hardware or your cloud, not ours. SentVi never sees or touches it, and the desktop version can run fully disconnected from the internet.
Start with the number you know and build outward
Rather than dumping every call onto a screen, SentVi lets you start with a single phone number and use Get Links to add its contacts one degree at a time, or pull its entire connected network at once. You can restrict it to only the calls the phone placed, only the calls it received, or only its direct contacts. As contacts are added, the links among them appear too, so a group of numbers that all call each other shows up as a group.
Find what connects your targets
When you have several numbers of interest, Between Selected adds the fewest entities needed to connect them, giving you the tightest network among your targets. Shortest Path and All Paths show every route between any two numbers, with a control for how many intermediaries to allow, and can filter the diagram down to just those routes. Two subjects who never call each other but share an intermediary become visible in one step.
See who the records have in common
As numbers are added to the diagram, SentVi shows the entities they have in common. Across multiple saved diagrams, its multi-Visualizer analysis produces the list of phones, devices, or license plates that appear in all or several of them. Five incidents in five locations, five sets of records, and the handful of numbers present in more than one. That list is usually short and always actionable.
Let the math point at the important phones
SentVi’s social network analysis scores every number in the network. Centrality measures identify the most connected phones. Betweenness identifies the phones sitting on the paths between groups, the spanners between cells, which are often the numbers a team would never have noticed by eye. Cliques, cutpoints, and disconnected networks can be viewed and filtered directly.
Filter by time, then watch it move
The temporal tools filter the entire network to a date range or a time window. Set it to the day of the incident, and the diagram shows only the contacts that happened then. Step it forward and watch numbers appear, go quiet, or start calling each other for the first time.
Put the cell sites on a map
Where the return includes cell site data, SentVi maps it on integrated online or offline maps, with export to Google Earth and support for ArcGIS. The map answers a question the network cannot: not whether two phones are connected, but whether they were in the same area at the same time.
Tag, share, and report
Numbers can be tagged with metadata such as Targeted, Subscriber Known, or Excluded, and filtered on it. Line thickness, labels, and colors can reflect call counts or any numeric value. Diagrams save to the database, can be merged, and can be shared with authorized users or handed to non-licensed reviewers through the free SentVi Reader. Output goes to Excel, PDF, Word, or image for the case file or the courtroom.
Who this is for
The records are the same whether they land on a detective’s desk, a private investigator’s laptop, or a litigation team’s shared drive. So is the analysis. What differs is the question: who the victim was talking to before the incident and who went quiet after; whether a departing executive was in daily contact with a competitor for six weeks before resigning; whether the timeline a witness swore to survives their own phone records; whether the same number connects three separate cases nobody had linked.
SentVi answers all of those from the same database, the same way, in minutes.
Where to start
The CDR analysis video below shows a raw carrier return entering SentVi and exiting as a network, a timeline, and a map. Watch it here or book a demo. Free trials are also available to test SentVi on your own records.
