Hello Dan,
To gather information from your user, you should use the IP Phone API.
Once you have it, you´ll be able to build XML definitions to input data and pass it as a parameter to a ASP/ASPX application endpoint.
Example:
<CiscoIPPhoneInput>
<Title>Your Application Name</Title>
<Prompt>...</Prompt>
<URL>http://[your_app_endpoint]/</URL>
<InputItem>
<DisplayName>Pin</DisplayName>
<QueryStringParam>UserPin</QueryStringParam>
<DefaultValue></DefaultValue>
<InputFlags>TP</InputFlags>
</InputItem>
</CiscoIPPhoneInput>
I hope it helps you!
Regards.
Breno Lucena