Introduction
Our agency lives on the phone. Tens of thousands of prospecting calls a year, made for B2B software companies across France, Spain and the UK. At that volume, the phone tool is no longer just another line item: it is the production tool. And like any production tool, it deserves better than a default choice.
Over two years we have used or tested seven solutions: classic VoIP carriers, CRM-embedded power dialers, an American parallel-dialing platform, and finally our own calling line, built in-house. Nearly 50,000 of those calls are now transcribed and analyzed in our platform. Here is what those tests taught us, and what we wish we had known earlier.
What you think you're buying, and what you're really buying
When you choose a phone tool, you think you are buying minutes and audio quality. In reality, you are buying three far more structural things: a number that shows up (or not) on the prospect's screen, data (or the lack of it), and a billing model. None of the three is printed in large type on the pricing page.
Lesson 1: your recordings aren't yours by default
On most platforms, a call recording is a URL hosted by the vendor. Those URLs expire, sometimes within 24 hours. The day you cancel, the history dies with your access. One of the solutions we used allowed, by design, no audio download at all: the calls made on it are unrecoverable.
We learned the hard way that you have to copy every recording to your own storage the moment the call ends, not the day you need it. If the tool does not allow it, that is a dealbreaker: those recordings feed SDR coaching, objection analysis, and proof in case of a dispute.
Lesson 2: call attribution is harder than it looks
Who made this call? The question sounds trivial. It is not: lines shared between several SDRs, duplicates (we saw one tool report the same call two or three times), an agent logged into a line that is not “theirs”. If attribution is wrong, every individual metric is wrong, and so is the compensation built on top of it.
Our rule today: attribute by the logged-in agent first, the line number only as a fallback. Few tools expose this information cleanly. Ask for it before you sign.
Lesson 3: caller ID has become an infrastructure question
This is the most counter-intuitive lesson. In France, since 1 January 2026, a call arriving via international routes that presents an unauthenticated French 06/07 mobile number is shown as “number withheld” (the MAN mechanism, under Arcep). Unauthenticated landlines have been cut since October 2024. (This is an operational observation, not legal advice.)
The practical consequence surprised us: we checked the same mobile number with two infrastructure providers. With one, it displays cleanly on SFR, Orange and Free. With the other, it comes through as “number withheld”, a setup their own interface had validated. Authentication is not a property of the number: it is a capability of the provider's infrastructure on its French route. No client-side setting can compensate.
Test with a real phone, on all three mobile carriers, before any commitment. An excellent tool whose number shows up withheld is unusable for prospecting.
Lesson 4: rounding up to the minute (almost) doubles the bill
A prospecting call is short: lots of no-answers, conversations of a few dozen seconds. On that profile, the difference between per-second billing and rounding up to the next minute is huge: on our numbers, minute rounding comes to roughly doubling the real telecom cost. It is a contract line no one reads, and it weighs more than the headline rate.
Lesson 5: without clean data, you're flying blind
Normalized call statuses, reliable transcription, webhooks that arrive on time: that is what separates a tool you endure from a tool you steer. Our best decisions of the year, what time to call, after how many attempts to stop, which lists are dead, all came out of analyzing our own calls. None would have been possible if the data had stayed locked inside the tool.
Why we ended up building our own line
No off-the-shelf solution ticked all four boxes at once: a number that displays cleanly, owned recordings, complete data, honest billing. So we built a pilot: a softphone inside our own platform, plugged into a wholesale telecom infrastructure, with a real, owned and verified mobile number.
What it changes: every call is recorded on our side, transcribed with the two voices separated, analyzed by our AI (opening, discovery, pitch, objections, closing), tied to the right prospect and the right SDR. The SDR sees an enriched record (memory of past exchanges, an opener generated from our data) before picking up. And the call stays sequential, by choice: a human calling with their own number is also what allows a clean mobile display under the current regulatory framework.
We keep using market solutions in parallel: building your own telephony only makes sense above a certain volume and with a technical team. But even if you build nothing, the criteria stay the same.
The checklist before you sign
- Can I download all my recordings, automatically, as soon as the call ends?
- Does the API expose the logged-in agent, not just the line?
- Does my number display cleanly on all three French mobile carriers? (Test it, take no one's word for it.)
- Is billing per second?
- Are statuses, durations and transcriptions exportable on an ongoing basis?
Conclusion
The right phone tool does not reveal itself in a demo. It reveals itself six months later, in the quality of the data it left you, or did not.
