Most VoIP comparisons answer the wrong question. They tell you which provider. The expensive question is what year one actually costs, and where the money leaks after the demo call ends.
I go through VoIP rollouts for small Vietnamese offices. This is the version of the decision I wish more teams made before they signed.
The published price is the smallest number in the deal
A per-user price covers the seat. It does not cover:
- The local number. Vietnamese numbers - 024 for Hanoi, 028 for Ho Chi Minh City, provincial codes elsewhere - are usually a separate line item from the seat price.
- The calls that leave the plan. Domestic calls sit inside the flat rate. International does not: expect 500-1,000 VND per minute, against 3,000-5,000 VND per minute on a traditional line.
- The parallel-run period. Running the old system and the new one side by side for a week is the correct way to migrate, and it means paying both bills that week.
- Hardware you may not need. IP handsets run $30-100 each, but a softphone on the desk or on a phone in a pocket is often enough. Take the free softphone first and buy handsets only for roles that genuinely need one.
Where the 40-60% saving actually comes from
The headline saving is real, but it is not spread evenly across the bill. In most Vietnamese offices it is concentrated in one line:
- monthly line rental: around 500,000 VND per line down to roughly 150,000 VND per user
- domestic calls: about 1,000 VND per minute down to included in the plan
- installation: around 2M VND per line down to self-setup
For a 10-person office the arithmetic usually lands in the 3-5 million VND per month range - but only after the parallel-run week is behind you, not on day one.
Self-hosting changes the shape of the cost, not the size
If you have someone who can run a server, a self-hosted PBX moves the spend from subscriptions to your own time. A small cloud VPS is normally enough for a five-to-twenty person office: the PBX, the call recordings and the extensions stay on a machine you control, so a failed update costs you a restore instead of a day without phones.
Two things to check before you commit: which data-centre region sits closest to the office, because round-trip latency shows up directly in call quality, and whether whole-server snapshots or backups are included rather than just the disk space.
Three questions to settle before you port numbers
Number porting exists in Vietnam and typically takes 5-7 business days. The provider handles the paperwork with your current carrier, but the date is a business decision, not a technical one:
- What happens to inbound calls during the port window, and who tells customers?
- Can you export call logs and recordings in a format your accounting and CRM tools can read?
- Which features are priced per user and which are priced per simultaneous call?
Test quality before signing, not after
Vietnam's average connection is comfortably above 50 Mbps, and one call needs roughly 100 Kbps, so raw speed is almost never the problem. Stability is. Before signing:
- ask for a demo during peak hours, not on a quiet morning
- confirm the provider can prioritise voice traffic with QoS rules
- confirm automatic failover to a mobile number when the line drops
- test in the worst-connected location you have, not at head office
Rural or single-line offices are where VoIP projects fail, and no pricing table will tell you that in advance.
When VoIP is the wrong answer
If the office runs on one unstable line with no second path, or the phone rings a handful of times a month, migration cost - parallel run, training, porting - can exceed the saving in year one. Run the arithmetic for your own line count before comparing providers. A cheap plan that nobody trusts is more expensive than the line it replaced.
The short version
- Model four cost lines, not one: seat, local number, out-of-plan calls, parallel run.
- The 40-60% saving is mostly line rental, and it arrives after migration, not at cutover.
- Self-hosting buys control; check region and snapshots before you commit.
- Test at peak hours and in the worst-connected office.
- Porting is 5-7 business days. Schedule it; do not discover it.
The provider-by-provider comparison, the feature table and the full implementation plan are in the original article: Best VoIP phone system for a small business in Vietnam.
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