Mine is not a Merlin, but my newest Boston Scientific pacemaker has a device like that. Mine connects to my pacemaker via Bluetooth technology, like connecting your cell phone to an earpiece or car system. It reads data from the pacemaker and sends an alert to the clinic if it notes anything outside the preset parameters. It also has a monthly schedule by which it performs a complete interrogation of the device and sends the report back to the clinic. With this system, instead of having to go to the clinic for interrogations twice per year, I only go once.
The device I have doesn't even require a phone line connection. It has an adaptor that links to one of the cellular phone systems directly.
I've had the system (and the new pacemaker) since early July, and the only times it has scared me were the two times when Boston Scientific updated the software of my communications system. When that happens, usually around 3:30 AM, the console flashes all of its colored lights so brightly that it awakens me from a sound sleep. The first time that happened, I thought my pacemaker had gone wonky! I called Boston Scientific tech support (and they are really great) and they explained what was happening. Then next time, I just went back to sleep.