The color of the line is insignificant. Pregnancy tests can only tell you if you are pregnant. The darkness of the line is no indication of how pregnant you are or how far along you are. You can use the brand tests, even from the same box and get a lighter or darker line any time.
The phantom calls that you have recieved, also known as ghost calls is usually caused by either a poor quality phone line, aka has a high amount of noise or foreign battery due to the line or your on an older copper line.
Reasons for a busy signal. An otherwise unspecified busy signal indicates that the called number is occupied: The called number is talking with another caller on the phone. The number is calling out, Someone else has called the number or is calling the number at the same time, The other line was left off-hook, It is otherwise unavailable.