Mobile and Work Phone

Outcome: a phone column gated on account value, with mobile and work numbers distinguished, validated where relevant, and never run twice for the same contact.

Surface: App and MCP server
Level: Beginner
Uses: find_mobile_number · find_work_phone · validate_whatsapp
Credits: ~2–5 per hit
Prerequisite: Lesson 03

The most expensive column in the course

Phone data costs several times what email costs and has lower coverage. That combination means it must be gated harder than anything else in your pipeline.

Never run it as a default column on every row. Gate on score, deal value, or a segment where email genuinely does not work.

Mobile versus work phone

	Mobile	Work phone
Reaches	The person	A desk, a switchboard, or a queue
Coverage	Lower	Higher
Cost	Higher	Lower
Best for	Senior contacts, high-value accounts, follow-up on engagement	Local business, SMB, anywhere the business is the target
Risk	Higher — a personal device	Lower

Reference: find_mobile_number, find_work_phone.

When phone beats email

Local and SMB segments

Email coverage is thin, shared inboxes are unread, and the phone number is on every page of the site. Often the primary channel rather than a fallback.

High-value accounts

When one deal justifies the research, the credit cost is irrelevant next to the conversion difference.

Follow-up on engagement

Someone who opened three times and did not reply is worth a call. This is the highest-converting phone use there is, and it is cheap because the population is tiny.

Regions where email is not the business norm

Varies by market. Check what your own reply data says rather than assuming.

Gate it properly


run_phone_lookup =
      score >= high_threshold
  OR  segment = "local_business"
  OR  (engaged = true AND replied = false)
  OR  estimated_deal_value > threshold

Four conditions, each defensible. Everything else does not get a phone lookup, and that is what keeps the column affordable.

Running mobile lookups across an entire prospect list is one of the fastest ways to exhaust a credit balance. At several credits per hit and a coverage rate well below email, a 2,000-row table can consume more on this one column than on the entire rest of the pipeline. Gate first, always.

Do not pay twice

Two rules that prevent duplicate spend:

Check what you already have. A number in your CRM is free. Look before you buy.
Order the lookups. Work phone is cheaper — try it first where a desk line would do, and only escalate to mobile where reaching the person directly matters.

And record which lookup produced each number, so a re-run does not repeat the expensive one.

WhatsApp validation

In markets where WhatsApp is a normal business channel, validate_whatsapp confirms a number is reachable there. Two uses:

Channel selection — a valid WhatsApp number in a market where that is normal is often a better route than a cold call.
Number validation — a number active on WhatsApp is a number in use, which is useful signal regardless of whether you message there.

Reference: validate_whatsapp, WhatsApp number validator.

The rules that apply

Calling is regulated more heavily than email in most markets. Before you run a phone campaign:

Do-not-call registries. Check the applicable ones. Some are legally binding with real penalties.
Consent regimes. Several jurisdictions require prior consent for business calls to mobiles.
Time-of-day restrictions. Common, and enforced.
Recording rules. Consent requirements vary by jurisdiction and sometimes by party.

Find out what applies in your target market before the first call, not after a complaint.

Do this now

Write the gate

Four conditions, or your own equivalent.

Check existing data first

Your CRM may already hold numbers you are about to buy.

Run work phone on the eligible set

Read the results — is it a direct line or a switchboard?

Escalate to mobile only where it matters

Senior contacts, engaged non-repliers, high-value accounts.

Validate WhatsApp where the market warrants it

Record the source per number

So re-runs do not repeat the expensive lookup.

Compute cost per number found

And compare it against your cost per verified email.

Check your work

The phone column runs behind a gate, not on every row
Existing CRM numbers were checked before buying
Work phone was tried before mobile where appropriate
Source is recorded per number
You know the calling rules for your target markets

Where this breaks

Treating a switchboard number as a direct line wastes a rep’s time at scale and looks unprofessional at the other end. Check what a returned number actually is before it enters a calling list — a main office line routed through reception converts very differently from a direct dial, and mixing them makes call-connect rates meaningless as a metric.

Further automation

Phone numbers decay more slowly than emails but more visibly — a disconnected number is obvious on the first call. Rather than re-enriching on a schedule, capture call outcomes back into the table and re-look-up only the numbers that failed. That feedback loop is cheaper and more accurate than any refresh cadence.

Next lesson

06 — Reverse lookup: email → profile, turning a list of bare addresses back into full records.

Reference for this lesson: find_mobile_number, find_work_phone, Find phone from email, validate_whatsapp.