One type of popular and well established modems are Motorola Surfboard (Arris) Modems. These modems have been a popular choice for both cable providers and users who purchase their own. Accessing your modem can give you a good indication of possible issues arising from inadequate signal strength or too much noise on the line that will affect the connection.
By accessing the screen pages inside your modem you should be able to gain some information on your Internet connection. Two important pages are the Status page and the Signal page, both showing a snapshot of information about your current Internet provider's Internet signal strength and potential possible issues that could affect your connection and ultimately your VoIP service.
Poor signal levels result in- Signal levels that are not in the acceptable parameters listed above can cause loss of connection, slow speeds and connection issues, including failure of one of the steps needed for registration with the provider, packet loss or the need for packet retransmission.
Premise hardware- On premise hardware including splitters, bad connectors, and poor quality cabling will effect cable signal levels and can cause problems. The cable modem should be a direct line from the first splitter using the leg with the least dB loss. This will allow the best level of signal from the cable box at the premise to reach the modem.
Signal level variation- Checking the modem's signal levels is a snapshot of those levels at that time. Weather and the change of temperatures affects cable hardware which can reflect in variations of the levels at the modem. It is recommended that for best performance some headroom is included in a modem's levels of approximately 3dB. Additionally, when checking the modem and finding variations that occur in a short period of time, where the signal level readings are varying sporadically is a cause for concern and may point to an issue that needs to be corrected.