How to build a cold calling list

Step 1: Who belongs on your cold calling list?

Write a one-line definition first: the trade, the area, the size and the person you want on the phone. Every row should match that line, or it should not be on the list.

Start from your best customers. What they share, such as trade, city size or review count, becomes your search filter.

82.3% of US small businesses have no employees, according to the SBA Office of Advocacy. For local trades, the person who decides is usually the owner, and the listed number often reaches them.

Source U.S. SBA Office of Advocacy

Step 2: Where do you get phone numbers for a cold calling list?

Five places to source a cold calling list, compared

Before paying for any list, ask for a sample, the read date and each row's phone type: where to buy business leads.

Step 3: Give every row the same fields

The columns a dialer-ready row carries

E.164 is the international number format: a plus sign, the country code, then the number. Phone type means mobile, landline, VoIP or toll-free.

Step 4: How do you know if a number is a mobile, landline or VoIP?

The area code cannot tell you. Under number pooling, carriers get numbers in blocks of 1,000. One exchange, the area code plus the next three digits, can hold wireless, landline and VoIP blocks side by side.

Guessing from the exchange gets 327,459 of 1,307,755 blocks wrong (25%), in Leadity's count of the NANPA block records, read 22 September 2026. That is about 1 in 4 guesses wrong.

The reliable check runs on the number itself, in four steps checked against carrier data: format, allocation, a carrier lookup and the line type. A ported number keeps its block, so the block alone cannot show where it sits today.

The type changes the call. A landline rings a desk; a mobile rings whoever carries it. FCC rules require consent before an autodialed or prerecorded call or text to a wireless number.

Sources Leadity FCC

Step 5: Do you need to scrub a B2B list against the Do Not Call Registry?

Most B2B sales calls are exempt from the Do Not Call provisions, according to the FTC. Calls to consumers, such as homeowners, are not: sync those numbers with the registry at least every 31 days.

B2B is not a free pass: under the rule the FTC announced on 7 March 2024, its misrepresentation ban covers business-to-business calls. The FTC says Do Not Call violators may be fined up to $53,088 per violation.

General information, not legal advice: ask a lawyer about your calls, and run the TCPA risk checker before you dial.

Source FTC

Step 6: How do you avoid calling reassigned numbers?

About 35 million US phone numbers are disconnected and made available for reassignment each year, according to the FCC's December 2018 order.

Under that order, a disconnected number must age at least 45 days before a new subscriber gets it. A list older than that can reach a stranger.

The FCC's Reassigned Numbers Database, open to paid subscribers since 1 November 2021, shows whether a number may have been reassigned.

Query it whenever you rely on consent collected earlier: that consent came from the old subscriber. If the database wrongly answers that a number was not reassigned, the caller may be protected from TCPA liability.

Source FCC

Step 7: Clean and dedupe the list

Step 8: Decide which leads to call first

Rank the rows before anyone dials. A tier: a mobile, a named contact and a clear fit. B tier: an office line at a good fit. C tier: VoIP, toll-free or a weak fit.

The mobile share depends on the trade. Of 2,241,697 businesses across 32 trades in Leadity's Q3 2026 Google Maps data, the share that list a mobile ran from 12.6% for software companies to 64.2% for real estate agents.

Two different shares: 36.8% of listed phone numbers are mobiles. Some businesses list no phone at all, so 31.2% of all businesses have a mobile.

Plan for voicemail: most people let an unknown number ring and check the voicemail, as the Pew figures above show. Then sort each tier by time zone.

Sources Leadity Pew Research Center

Step 9: Load the list into a dialer or CRM

• Export a CSV with named columns; dialers and CRMs import CSV files
• Map phone, phone type, time zone and contact name before importing
• Send mobiles and office lines to separate call queues
• Copy your do-not-call list into the dialer's suppression list
• Run a small test batch and count how many numbers connect

Step 10: Decide how often to refresh the list

Refresh before every campaign, and sync at least every 31 days for any number the Do Not Call Registry covers, as the FTC requires.

Businesses move, close and change numbers, so a list ages from the day it is read. Rebuilding from a live source can be quicker than repairing an old file.

Source FTC