RingCentral Webhooks - caller phoneNumber shows extention number instead of actual mobile number

We have created Webhook Subscription for getting missed calls.

We are using "/restapi/v1.0/account/~/telephony/sessions?direction=Inbound&missedCall=true" to get all missed calls/voice calls.

Webhook works good as we get all call information but somehow for some number we get only extention value(101) instead of phone number i.e

  [to] => Array
                                (
                                    [phoneNumber] => 101
                                    [name] => Sneha Rao
                                    [extensionId] => 712273005
                                )

.

is there any way to get actual phone number instead of extention number?