A method for performing a telecommunication service includes: obtaining, in a first message from a mobile device and by a processor, a first phone number to whitelist, where the mobile device is registered with a call screening service, and where the first message is a text message; storing the first phone number in a whitelist, where the whitelist comprises a plurality of phone numbers allowed to contact the mobile device; determining that the mobile device is roaming; activating, by the processor and in response to determining that the mobile device is roaming, the whitelist; receiving, after activating the whitelist, a second message for the mobile device from a second phone number; searching, by the processor, the whitelist for the second phone number to generate a failed search; and discarding, by the processor, the second message based on the failed search.