Short answer: one-way masking lets one side call the other but not the reverse. Two-way masking lets either party dial the same virtual number and reach the other, with routing deciding who they get based on who is calling. Most real use cases need two-way, because the call the customer wants to make is usually the one one-way blocks.
Edesy supports two-way masking through the Session API, included at ₹1.50/min rather than priced as an upgrade.
The Difference in One Table
| One-way | Two-way | |
|---|---|---|
| Who can start a call | One designated side only | Either side |
| What the other side sees | A number that does not accept calls back | The same working virtual number |
| Typical failure | Customer calls back, nothing happens | — |
| Numbers consumed | One per session | One per session |
| Best for | Outbound-only notifications | Anything transactional |
Note that two-way does not cost more numbers. Both directions run through the same virtual number in the same session, so the pool sizing is identical.
Where One-Way Genuinely Fails
The pattern is always the same: you masked the outbound call, the customer missed it, and they try the number back.
- Delivery. Agent calls, customer is in a lift. Customer calls back thirty seconds later and gets nothing. The order goes undelivered and the support cost exceeds a year of masking spend.
- Field services. Technician is outside, cannot find the gate. Customer sees a missed call and cannot return it.
- Recruitment. Recruiter calls, candidate is in a meeting. The candidate cannot call back and your funnel loses them.
In each case the second call is the valuable one, and one-way is precisely the configuration that drops it.
Where One-Way Is Actually Correct
It is not always the wrong answer:
- Automated outbound notifications where no reply is expected — an OTP delivered by voice, an automated reminder. There is nobody to call back.
- Compliance-constrained outbound where inbound calls must be routed to a monitored queue rather than back to an individual agent.
- One-shot verification where the session is over the instant the call ends.
If a human on the receiving end might reasonably want to call back, you need two-way.
How Two-Way Routing Decides
Both parties dial the same virtual number. The platform looks at who is calling and bridges them to the other party in the session. The buyer reaching that number gets the seller; the seller reaching it gets the buyer. Neither ever sees a real number.
Because routing is by caller, the same virtual number can safely serve both directions without ambiguity — as long as a number represents exactly one active pair at a time. That constraint is what drives pool sizing.
Session Lifetime
A two-way session does not have to be short. On Edesy a session can run from a minute to 30 days, or persist with no expiry for an ongoing relationship, and can be extended, paused, resumed or ended at any point.
Two patterns are common:
- Transaction-scoped: the session lives as long as the order. Ends on delivery.
- Relationship-scoped: a long-lived or persistent pair for an ongoing arrangement — a tenant and a property manager, a patient and a clinic.
Choose deliberately. A session that never ends is a permanent connection between two people, and that is a decision rather than a default.
What Neither Direction Solves
- Masking is voice. It does not cover SMS or WhatsApp — if your parties also message, that is a separate channel decision.
- Neither direction prevents someone reading a number out loud on the call.
- Neither is anonymity from the platform. You still hold both real numbers, which is what makes dispute resolution and compliance possible.
Choosing
Ask one question: if the person who received the call missed it, do you want them to be able to call back?
If yes — and for anything transactional it is yes — use two-way. See two-way masking, or start a session on the self-serve portal and try both directions from two phones before you integrate.