Modify Caller ID details on inbound calls

Description: We require an enterprise solution to displaying the correct caller ID on an Android phone that is receiving a diverted call. Example: With staff outside the office calls are diverted by our phone system to their Android phone. Our phone system uses a GSM gateway with a mobile phone sim card to divert the call. Due to this the caller ID received by staff on their Android phone is always the CID of the mobile phone sim card in the GSM gateway. App Outline: The app will be required to receive CID information from our corporate PBX system for calls that are being diverted to staff outside the office. The transmission of the CID from our Corporate PBX to the Android phone can be done via http or SMS, however the CID data will need to be "Pushed" to the Android phone instantly and in realtime as the incoming call is being diverted to the Android phone. Once received by the app this CID data will need to be stored and displayed in place of the incoming CID of the GSM gateways CID on the "incoming call screen" of the Android phone. As we only want the incoming caller ID of calls from our GSM gateway to be modified we will need to verify the GSM gateway CID in the app. The app will need to store (and receive updates to) a small list of CID's from our GSM gateway (only about 10 CID's that might change about once a month). When a call is diverted by our corporate PBX to the Android the app will instantly receive the correct CID for this call (via http or SMS) as the diverted call is received by the android phone the app will crosscheck the CID with the list of GSM gateway CID's, when there is a match the app will then modify the CID of the incoming call with correct CID received only milliseconds earlier. The correct CID is to be displayed on the "incoming call screen" and also kept in historical call data logs. The integration of the PBX server will also be a custom program. This may be done by local programmers but can also be added to this project if you have the required knowledge of Asterisk / PHP / MySQL etc.