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Frequently Asked Questions

Most questions are answered here. If not, contact us and we'll give you an answer.

All Questions

Q: Does the device block robocalls by itself?

No. Call Silencer works in conjunction with a server-based call blocking service such a Nomorobo.

Q: Will Call Silencer let through automated calls from the school or police department?

Yes.  By leveraging FTC whitelists: school, police, fire, emergency, bank, and pharmacy, legitimate robocalls calls are allowed through.

Q: Will Caller ID work properly on other telephony devices?

Yes. Caller ID works properly on all devices including telephones, fax machines, answering machines, and Caller ID devices.

Q: For legitimate calls that ring more than once, does the Caller ID come through to the phones?


Q: Will a blocked call show up on my caller id list?

No. Since no call rang through.

Q: Will a legitimate call show up on my caller id list?

Yes. Since the call rang through.

Q: Will Call Silencer silence “anonymous” calls where no number is displayed on a caller id display?


Q: Do I need to have a Caller ID subscription with my cable phone provider?

Yes. However, Caller ID is now a standard feature with phone service providers. At the simplest level, Caller ID is used to know what numbers to block and what numbers to allow through.

Q: Will legitimate incoming calls ring through on multiple, separate, individually wired phones?

Yes. Connect your phone network into Call Silencer and connect Call Silencer directly to your cable modem.

Q: Is there a REN (Ringer Equivalent Number) limit?

Call Silencer does not impact the REN from your cable modem. The standard is 5.0 REN. Moderm telephones with a bell that rings have a REN of 1.0. Cordless phones usually have a REN of 0.4. An old candlestick telephone with the big metal ringer box typically has a REN of 1.5 to 2.5.

Q: If a call is blocked, will the phone ring at all?

No. Blocked calls do not ring even once.

Q: Will Call Silencer work with a phone with multiple handsets?


Q: Will Call Silencer work in conjunction with an older generation hardware robocall blocking device such as CPR Call Blocker?

Yes.  Keep your hardware robocall blocking device connected where ever it is on your phone network.  Connect your phone network to Call Silencer. Connect Call Silencer to your cable modem.  

Q: Does Call Silencer work with cell phones?

No. It is designed exclusively to work with landline phones.

Q: What type of landline services does it work with?

It is designed for VOIP (Voice-over Internet Protocol) lines. These are the type of line used by cable service providers.  It is not designed for POTS (Plain Old Telephone System) lines from the old telcos.

Q: Which cable phone services is it compatible with?

All major cable phone services in the USA and Canada are supported, including: Astound (wave), AT&T U-verse, Broadvoice, Charter Spectrum, Comcast Xfinity, Consolidated communications, Frontier Communications, Ooma, optimum, RCN, Sonic, SureWest, Time Warner Cable, Verizon Fios, VoIPms, VOIPo, Vonage, wave.

Q: If I have multiple phones, are multiple devices required?

No.  Only one Call Silencer is needed.  Connect Call Silencer into the cable phone modem.  Then connect the phone network line into Call Silencer.  It will block the calls on all lines on the home phone network.

Q: Does it work with a 2-line phone?

For a two-line phone (e.g. home and home office; or dual business lines) you will need two splitters: one male to dual female (MDF) splitter and one female to dual female (FDF) splitter, two one-foot male to male (M2M) telephone line cords, and two Call Silencer devices. (1) Connect the MDF splitter to the cable phone modem. (2) Run a telephone wire from each port in the splitter to the “modem” side of each of the two Call Silencer devices. (3) Run a telephone wire from the “phone” side of each of the Call Silencer devices to the FDF splitter. (4) Connect your home phone network line into the FDF splitter.

RJ11 male to dual female MDF splitter

RJ11 female to dual female FDF splitter

Two 1-foot male to male M2M line cords

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