AT&T RELEASE 2 - Manual (Page 43)

FIGURE 32 MERLIN Plus system alerters.
FIGURE 33 MERLIN Plus system CO line wiring accessories.
Supplemental alert adapters allow you to connect alerting devices such as
horns, bells, and strobe lights to your system. See Figure 32.
See Figure 33 for other Central Office (CO) line accessories and voice terminal
wiring accessories.
To add accessory equipment to your system, follow the instructions that come
with the components.
Step 5: Adding Accessories 39