Many residential users or possibly a busines user have their service connected with an ATA analog VoIP adapter to a small phone home system with an answering machine.
If your Strategic Voice Solutions service for this number has the Voice Mailbox turned on and the answering machine is set to pick up after 5 or more rings, the SVS mailbox will pick up and take the message. When a message is on SVS and you have a ATA analog phone adapter it will present a stutter to your dial tone. If the local phone system or answering machine detects that your phone line is stuttering, it may think there is a message and it does not care where the message resides.
If your phone system/answering machine is set to answer on two rings when there is a message, this may cause a possible problem. You may try to call your own number to reach someone in the house and it will ring 2 times and go directly to the answering machine even though the answering machine does not have messages.
Normally this would mean you have a new message on your local answering machine and its alerting you to check it. In this scenario with the message residing on SVS it would keep the phone from ringing at the house, possibly long enough for someone to pick up or think the caller hung up.
The Solution: In most cases you would just turn on off the SVS voice mailbox and let the answering machine from the phone system take all messages. You could let SVS take all the messages and turn of the phone system answering machine. The choice is yours.