Validate that Skype username is in use - validation

Question

Is there a way to validate that a Skype username is valid in a web app? (form validation upon account creation)
By valid, I do not mean by using regular expressions. We can easily check to see if it is 6-22 characters, starts with a letter, etc. I want to verify that either:
the username entered actually calls the user inputting it, similar to when we validate email by sending an email with a link to verify it or
verify that there exists in the Skype database a user with that username.

Answer 1

This may not be very reliable, but the following endpoint will give you different responses based on the availability of a Skype username: https://login.skype.com/json/validator. Here are two examples of (at the time of this writing) an unavailable and available username:
# Request (unavailable):
curl -iX POST -H" Application/json" https://login.skype.com/json/validator?new_username=borist
# Response:
{
"status": 406,
"status_text": "valid",
"data": {
"markup": "Skype Name not available",
"alternatives": true,
"fieldDetails": "<label>Suggestions<\/label><ul><li><label><input class=\"skypeNameSuggestion\" type=\"radio\" name=\"selectSkypeName\" value=\"borist92\"\/>borist92<\/label> <\/li><li><label><input class=\"skypeNameSuggestion\" type=\"radio\" name=\"selectSkypeName\" value=\"borist176\"\/>borist176<\/label> <\/li><li><label><input class=\"skypeNameSuggestion\" type=\"radio\" name=\"selectSkypeName\" value=\"borist417\"\/>borist417<\/label> <\/li><\/ul>"
}
}
# Request (available)
curl -iX POST -H" Application/json" https://login.skype.com/json/validator?new_username=boris3294a
# Response
{
"status":200,
"status_text":"valid",
"data":{"markup":"",
"alternatives":false,
"fieldDetails":""}
}

Answer 2

I guess you'll have to do exactly what you said: “similar to when we validate email by sending an email with a link to verify it”
I'd dig into Skype4py, you'll find an example of searching for someone.
So you can do:
some kind of early validation by searching for that person
sending him/her a txt message with a key/link to verify your user
See: need an python script that uses skype4py to send an instant message

Answer 3

Building off of pho79's answer, I have made a gist. The code simply checks to see if the message returned says that the name is unavailable meaning that it is in use. There are some other messages it sends back for other errors, so this is what I went with.
import requests
def checkName(name):
values = { "new_username" : name }
r = requests.post("https://login.skype.com/json/validator", values)
return "not available" in r.json()[u'data'][u'markup']