Mobile vs Landline vs VoIP
The three primary phone-line classifications — mobile (cellular), landline (POTS or modern equivalent), VoIP (internet-routed) — each with different reachability and cost implications for outbound agency calls.
Mobile numbers are the gold standard for agency outbound: they reach an actual human, are SMS-capable, and the owner is the most likely person to respond. Landline numbers reach the business front desk during hours but answer rates drop ~60% after 5pm. VoIP numbers split into two flavors: fixed-VoIP (provisioned to a physical address, behaves like a landline) and non-fixed-VoIP (Google Voice, Skype, defunct registrars).
The non-fixed-VoIP bucket is the silent killer of cold-call lists. Many older business listings carry non-fixed-VoIP numbers that were valid five years ago but now ring into voicemail nobody checks. Filtering them out before dial reduces wasted dials by 20-30% on a typical local-business list.
For agencies: pull the mobile bucket first for SMS-or-call sequences, the fixed-VoIP and landline bucket second for daytime call sequences, and skip non-fixed-VoIP entirely on cold lists older than 12 months.
Related terms
- Line Type DetectionClassifying a phone number as mobile, landline, or VoIP by querying carrier databases — critical for distinguishing dialable real numbers from defunct VoIP forwards.
- TCPA ComplianceAdhering to the Telephone Consumer Protection Act — the federal law governing outbound calls and texts in the US, enforcing consent rules, calling-time windows, and DNC respect.
Run a free scan in your real market
Three scans, no card. See the score, line type, DNC, and CRM-ready export in action.