Currently MDC asks for Sender ID, when user creates Android push binding. But this ID is not used anymore:

• it is ignored by MDC (not applied to android variant cr)
• it is ignored by push operator (always set to "1" [1])
• and it is also ignored by UPS (push notification are still successfully received by devices even without correct sender id)

[1] https://github.com/aerogear/unifiedpush-operator/blob/master/pkg/unifiedpush/client.go#L179