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BLE Advertisement and UUIDs

I have questions related to use of UUIDs. Any help would be grateful.

The following are the UUIDs that are seen from our peripheral device during advertisements and after connection. 

During Advertising


After connection (without authentication), the following service & characteristics can be discovered:

“6E400001-B5A3-F393-E0A9-E50E24DCCA9E”  // UART service

“6E400002-B5A3-F393-E0A9-E50E24DCCA9E”  // Read characteristic (to allow write from external device)

“6E400003-B5A3-F393-E0A9-E50E24DCCA9E”  // Transmit characteristic (to notify external device)



1.  As we are using (6E40xxxx-B5A3-F393-E0A9-E50E24DCCA9) anyone looking at our advertisement packets knows that we have NORDIC UART service. 

Since only our apps need to communicate with the device, do we still need to use the well-known published base-128-bit UUID from Nordic for UART?  Our apps already know that we are using UART service over BLE.  Do we need to advertise it to everyone?

2. Can we change/mask the number? Does changing the number affect the Nordic stack behavior for UART?

3. The Bluetooth Core Spec says that we have to use the company IDs, and assigned IDs whenever possible. We do have reserve company Ids and couple of UUIDs with the BT SIG. Can we use these reserved numbers in our advertisement and services? Is there any impact of using or not using these to the UART Service?