Yes we do! Actually we have a couple of options for you here. They are all dealt with by making edits to your Call Routes in your Dashboard. They can be found at Dashboard > My VoIP > Routing > Call Routes.
1) If you don't have your calls terminating to a mailbox, then you simply put an external number on the end of your call route as your backup and if we can't connect with you on any of your previous steps (Which would be your internal users and or groups), we automatically skip those steps and go straight to the external number at the end. In normal cases that step will never be reached as in the internal steps you will have specified ample call ringing time to cover yourself.
2) If you are finishing your call route with a mailbox, much like (1) above any internal steps will be automatically skipped and your caller will go straight to your mailbox, where upon they can leave a message and we will notify you instantly via your notification email address.
Note that for this to work your client device (Softphone or Hardware) needs to have de-registered with the Yay.com Platform. Its quite likely that if you lose your data connection that will not have happened gracefully, so therefore there may be a short delay in this kicking in until your devices "time out" with the Yay.com platform. This "Session time" is something you specify in the settings of your device.
To give you an example of the default settings, the softphone Bria from Counterpath is set as default to 3600 seconds (60 minutes). Grandstream hardware phones are set to 60 seconds. Both can be changed in their preferences/configuration on a per SIP account basis. So in a worst case scenario, a Grandstream hardware phone would kick in after 60 seconds and if using Bria, after 60 minutes. Remember at the point of failure you could already be some way through this "session time" period, so it may kick in quicker. EG: I'm using a Grandstream phone which has a 60 second registration period. It last registered 40 seconds ago, my broadband then goes down - I will only need to wait 20 seconds before my back up is in action.