When using SMS authentication, the OneSpan Sign evaluates the phone number provided in the request payload to determine how it should be interpreted and validated. Understanding this behavior helps ensure that phone numbers are correctly processed and that authentication messages are delivered successfully.
If a phone number contains exactly 10 digits with no leading + sign, OneSpan Sign automatically assumes that the signer is located in North America. In this case, the country code 1 is appended to the number before it is stored or returned in the response payload.
For example:
5551234567 becomes 15551234567
This behavior applies only when the number is 10 digits and does not include an explicit country code.
Some countries also use 10‑digit phone numbers by default. If the signer is located outside North America but their number still consists of 10 digits, you must include a leading + in the request payload. This ensures the system does not incorrectly assume the number belongs to the North American numbering plan.
For example:
+5551234567
Phone Number Preprocessing and E.164 Formatting Guidelines
In addition to the SMS Phone Number validation described above, OneSpan Sign also uses a preprocessing workflow that sanitizes and standardizes all inputs into the internationally recognized E.164 format. This ensures that numbers are stored and returned in a consistent structure across all APIs.
E.164 is the global standard for international telephone numbering as defined by the International Telecommunication Union (ITU). It defines how numbers should be structured so they can be recognized and routed anywhere in the world. An E.164 phone number includes:
A maximum of 15 digits
Digits only (0–9)
No spaces, hyphens, parentheses, or other separators
A leading
+to indicate an international number
OneSpan recommends that you submit phone numbers directly in E.164 format. However, our system also accepts several alternative user‑entered formats and standardizes them automatically. This means that we accept various formatted inputs and convert them to the correct E.164 structure during preprocessing.
For example, we accept inputs such as:
(+32) 0470123456
Even though this example includes parentheses and a leading zero after the country code, our preprocessing removes the non-digit characters and the leading zero, and returns it in E.164 format:
+32470123456
The use of a leading zero is accepted by most European countries, but may not be accepted by all. The use of a leading zero is not accepted for North American numbers.
The Get Package API will always return the phone number in this standardized format.
+ [Country Code] [National Destination Code] [Subscriber Number]
Here are some examples of E.164 numbers:
Country | Example (E.164) | Explanation |
|---|---|---|
United States/Canada | +14155552671 | +1 = country code |
United Kingdom | +442079460123 | +44 = UK |
France | +33142278186 | +33 = France |
India | +919876543210 | +91 = India |
Correct Number Format | Incorrect Number Format |
|---|---|
+14155552671 | (415) 555-2671 +1 415 555 2671 0044 20 7946 0123 |