Numbering
The layer a caller actually touches. Its failure is the most commercially expensive of the four, because it is invisible to you and immediately obvious to them.
- Geographic, national and toll-free ranges
- A guaranteed terminal destination on every number
- Volume and outcome reported per range
What this layer does
A number here is an entry in a routing table rather than an attribute of a circuit. Someone dials it, the call reaches the platform, and rules you control decide where it goes — a site, a group, a queue, a mobile, an announcement, or somewhere different depending on the hour.
That decoupling is what makes numbering useful as an instrument rather than an administrative detail. Distinct ranges for campaigns, regions, product lines or partners, each routed independently and reported independently, all terminating into the same control layer.
The defining requirement is that a published number is never unreachable. Every evaluation path terminates at a defined destination, including when every preferred destination has failed simultaneously. That is not a nicety; it is the whole boundary condition of this layer.
The layers within
Four sub-boundaries, three of which are regulatory rather than technical.
Eligibility
Establishing whether a range can be held at allRegulated per country and per range type. Several jurisdictions issue geographic ranges only to organisations able to evidence a local address. Confirmed before a date is committed.
Evaluation
Deciding where a call goesTime, day, holiday calendar, caller region and destination state, evaluated in order, always ending at a guaranteed terminal destination.
Authority
Controlling what may be presented outboundOutbound presentation permitted only for ranges over which authority can be demonstrated, within the caller identity rules of the relevant country.
Custody
Preventing a range being takenPort-out requests verified against account authority before action; routing changes restricted by role and individually attributed.
- A published number reaching an undefined destination because a rule chain ran out
- A range being ported away without proper authorisation
- Outbound presentation of a number the organisation cannot demonstrate authority over
- A geographic range obtained where local regulation did not actually permit it
- A port rejected because submitted account details did not match the losing provider's record
What this layer protects against
Numbers are identity, and the risks reflect that more than they reflect telephony.
How it is fitted
New ranges are quick. Ported ranges are governed by timelines outside anybody's control.
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Measure
Which countries, which range types, what each range is for, and what each should be able to measure.
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Specify
Eligibility confirmed per range, and the rule chain including the terminal destination written down.
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Prove
Every rule exercised against the range before it carries production traffic.
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Fit
Ported ranges cut over at a scheduled time and verified immediately, previous path retained until confirmed.
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Hold
Per-range volume and outcome reported and reviewed; routing changes attributed and logged.
What this layer produces
Per-range reporting
Volume, answer rate, abandonment and duration by number, so channels compare honestly.
Rule chain record
The evaluation order and terminal destination for every range, documented and yours.
Authority evidence
What was relied on to permit outbound presentation for each range.
Numbering inventory
Every range held, its type, its jurisdiction and its current routing.
Sometimes. It depends on coverage and on local regulation; several countries restrict geographic ranges to organisations able to evidence a local address. We confirm the specific range rather than publishing a map.
That every rule chain ends somewhere defined. Even where every preferred destination has failed at once, the call reaches an announcement or a mailbox rather than an undefined outcome.
It is set by the losing provider and the local process, and we do not control it. We state the expected duration at specification rather than promising around it.
Only ranges over which you can demonstrate authority, within the caller identity rules of the relevant country. We will not configure presentation of a range you cannot show authority over.
No. Ranges can terminate into a phone system you already own over a trunk, or into a third-party platform during a transition.