If you believe that a phone number is returning an incorrect result, first test it with libphonenumber via their Online Demo.If that returns the same result as this project, and you feel it is in error, raise it as an Issue with the libphonenumber project.
These are "input format", "valid number range and valid number length for this range", "storage format" and "display format".
Many systems try to constrain the user to typing numbers in a particular format, and this is usually a very bad idea.
As a result, jumps in major versions may not actually contain any backwards incompatible changes. Google try to release their versions according to Semantic Versioning, as laid out of in their Versioning Guide.
Let's say you have a string representing a phone number from Switzerland.
I'm not sure about 5.3.4 final, but it is written that some 5.3.4-snapshot versions also were affected.
I am having trouble getting my PHP to correctly validate phone numbers.
There could be additional releases where needed to fix critical issues that can not wait until the next release from Google.
This does mean that this project may not follow Semantic Versioning, but instead Google's version policy.
Many of your customers and prospects now expect to be able to complete their entire interaction with you via their handheld device.