Ashveej,
What's happening is that call.ani returns "tel: +1234567890", which is the string that gets sent to Salesforce by the data action. Unless your phone numbers are stored in Salesforce with the "tel:" at the front, this isn't likely to produce a match.
You'll want to do something like: ToPhoneNumber(Call.Ani).subscriberNumber
This will send only the subscriber number from the inbound caller as part of the data action.
Note that this could also produce some interesting results if the subscriber number value is not set, and you'll want to account for that or the flow could take the default error handling path. Something like this should handle that scenario:
If (IsSet(ToPhoneNumber(Call.Ani)) and ToPhoneNumber(Call.Ani).isTel, ToPhoneNumber(Call.Ani).subscriberNumber, "")
There's more info on the PhoneNumber data type here: About the phone number data type - PureCloud Resource Center
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Richard Schott
Genesys - Employees
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