Outboundless Improves Cold Call Connect Rates by 4x with Phone Validation API
Overview
Outboundless, a cold calling agency, lifted connect rates from under 5% to over 20% by filtering lead lists with Trestle’s Phone Validation API. The team discovered that roughly 30% of “mobile” numbers they were receiving from mainstream B2B providers were actually mislabeled, eating into the dial volume their clients pay for. With line type and Phone Activity Score data from Trestle, Outboundless now validates every call list before reps start dialing, boosting connect rates and conversations for their clients.
The Challenge
Outboundless contracts on dial volume, which meant every disconnected line or mislabeled mobile number would directly erode the value clients pay for. The team found that mobile contact lists pulled from mainstream B2B data providers were unreliable, with roughly 30% of numbers labeled as mobile turning out to be landlines, fixed- or non-fixed VoIP lines. This resulted in dead dials, wasted rep time, and threatened their campaign performance, client retention, and ability to deliver consistent results. Recognizing this challenge, Outboundless sought a way to validate line type and phone activity before reps started dialing. Their goal was to clean lead lists at scale, prioritize the most contactable numbers, and deliver better outcomes for clients faster.
The Solution
Outboundless integrated Phone Validation API to clean and prioritize lead lists before any campaign went live. Using the Batch Upload feature, the team submitted contact lists and received line type and a Phone Activity Score for every number, allowing them to filter out mislabeled phones and deprioritize numbers with Phone Activity Scores below 30. By focusing dial volume on validated mobile numbers with strong activity signals, Outboundless was able to ensure reps spent their time on the contacts most likely to ring through to a real person. The team got up and running quickly at first with a free trial, then moved to the Trestle and Clay integration, and received hands-on guidance from Trestle team member Cameron Hembree to get insights on how to interpret scores and structure their workflow.
The Impact
By leveraging Phone Validation API, Outboundless boosted the connect rate on their cold call campaigns from <5% to over 20%, a 4x improvement that translated directly into more conversations, more booked meetings, and better outcomes for their clients.
On campaigns where the team ran the same client list with and without Trestle’s data, the difference was very apparent. Before Trestle’s data, the time they spent calling resulted in very few connections. With Phone Validation API, that lead list would turn into multiple meetings booked per day.
Beyond campaign performance, accurate mobile data has become a competitive differentiator for the agency, allowing Outboundless to offer list cleaning as a standalone service and giving them a clear edge in an industry where client retention is a constant battle. As a result, Outboundless has reinforced its position as a results-driven cold calling partner for their clients.
Why Trestle
Outboundless chose Trestle for accurate, reliable mobile data and a support experience that helped the team get value from day one. Phone Validation API delivered the line type and Phone Activity Score data Outboundless needed to filter out mislabeled numbers and prioritize the most contactable leads, with the coverage and accuracy to support a business model where every dial counts.
The Clay integration and Batch Upload feature made implementation straightforward, while hands-on guidance from the Trestle team helped Outboundless interpret scores and build a workflow that scaled across client campaigns. With Trestle as a trusted data partner, Outboundless can confidently deliver stronger connect rates, better client outcomes, and a competitive edge in the agency space.
Outboundless rated Trestle 5 out of 5
across all categories:
API reliability and uptime
Data quality and accuracy
Ease of integration
Documentation quality
Support responsiveness
Likelihood to recommend
Overall business value
Overall satisfaction
About Trestle
Trestle provides industry-leading phone data APIs to improve lead management and call operations for businesses. Trestle’s product suite is powered by a cutting-edge identity data graph built on top of modern, scalable technology and machine learning capabilities that have yielded the best-in-class coverage and accuracy. This, along with a network built on top of 500MM+ queries every month, enables Trestle to serve with a differentiated product suite that businesses rely on for various use cases, including caller identification, call routing, lead assessment, and prioritization.