The Basics of Corporate Mobile Phones
Corporate mobile phones are business-only devices issued by companies to employees. According to METI's SME survey, about 80% of companies with 50+ employees have implemented corporate phones. Understanding the cost, security, and operational trade-offs versus BYOD helps you pick the right approach. Corporate sales primers are also useful context.
Carrier Characteristics
Big 3 (Docomo, au, SoftBank)
The big three offer dedicated corporate desks, volume discounts, dedicated account managers, and 24/7 support. Standard rates are 4,000-7,000 yen per line per month, with bundled data and voice plans. Multi-line discounts (10+ lines) make these attractive at scale.
Rakuten Mobile
Rakuten offers dramatic pricing at 1,078-3,278 yen per line, with unlimited data and domestic calling. Popular among SMBs and startups, it's expanding share in venture-company corporate fleets. Coverage gaps remain in some areas, so on-site testing is essential.
MVNO (low-cost SIM)
IIJmio, mineo, UQ Mobile, and others run 1,000-2,500 yen per line. For data-centric work (sales map checks, email, groupware), they're entirely viable. Voice costs extra, so they're poor fits for high-call-volume roles.
Compared With BYOD
BYOD pros
- Lower initial and monthly costs (0-2,000 yen monthly stipend including device subsidies)
- Employees pick their own devices
- No second device to carry
BYOD cons
- Business data sits on personal devices - higher post-employment leak risk
- Personal numbers become known to customers, generating post-employment contact
- Security policies (password strength, app restrictions) can't be enforced
- Damage and loss become personal liabilities
As covered in choosing a business phone number, separating work and personal numbers is fundamental. Even with BYOD, using a softphone via cloud PBX achieves separation.
Device Selection Criteria
Required specs
Match specs to use cases. Sales: camera quality (business cards, site photos). Management: battery life (long meetings). Engineers: processing speed (remote dev). Field workers: ruggedness (drop resistance).
iPhone vs Android
For confidentiality, iPhone wins (centralized management, long security patch support). For cost, Android wins (more model choices, cheaper options). MDM (Mobile Device Management) supports both well.
2-line use via eSIM
iPhone, Pixel, and other eSIM-capable devices can host both corporate and personal lines on one phone, via physical SIM + eSIM or dual eSIM. This avoids two-device hassle while still separating work and personal by phone number.
Cost Management in Practice
Routine plan review
Analyze usage (call minutes, data) periodically and downgrade overprovisioned plans; upgrade if overage charges are appearing. Annual reviews are a good rhythm.
Usage rules
Codify rules around personal use, off-hours calls, and overseas roaming. Specify who covers excess charges (employee, payroll deduction, etc.) when rules are violated.
Hybrid with landlines
Field-heavy roles get corporate mobiles; desk-bound roles get landlines plus softphones. Receive toll-free inquiries on the landline side and originate outbound on corporate mobiles for cost efficiency.
Cancellation and Device Refresh
At employee separation or device refresh: (1) wipe device data completely, (2) deregister from MDM, (3) decide whether to retain or release the number, and (4) ask the former employee's contacts to delete the number. See phone number change procedures. Corporate plans typically allow MNP to other carriers - useful as a cost-review lever.