90v at 20-30hz and about 20ma I believe. Normal phone lines will supply upwards of 100ma, but since you only need to ring one ringer, you can do with less, you

90v at 20-30hz and about 20ma I believe. Normal phone lines will supply upwards of 100ma, but since you only need to ring one ringer, you can do with less, you can also tune the ringer to make it more sensitive.