# ＊ NewNumberMapper
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The `NewNumberMapper` creates and applies a consistent mapping between real numbers and fake, synthetic numbers. The mapping preserves the geographical context of the phone numbers. That is, numbers belonging to a region are mapped to fake phone numbers in the same region.
```python
from rdt.transformers.phone_number import NewNumberMapper
mapper = NewNumberMappper()
```
## Parameters
**`default_country`**: If phone number does not have an international country code, provide the country code to use.
(default) None
No default country. All phone numbers must have international country codes.
### Examples
```python
from rdt.transformers.phone_number import NewNumberMapper
mapper = NewNumberMappper(default_country='US')
```
## Attributes
After fitting the transformer, you can access the learned values through the attributes.
**`mapping`**: A dictionary that maps the original, real phone number to a new, fake phone number
```python
>>> transformer.mapping
{
'(617)253-3400': '(617)100-1234',
'(617)253-2142': '(617)555-2223',
...
}
```
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