Current Month Phone Spam Call Blocking Effectiveness
Spam telephone calls from “Rachel at card holder services”, “your Google listing has not been optimized” and numerous others are an annoyance that has become a major problem. Stopping Rachel from Cardholder Services covers multiple ways to address phone spam, including
- Turning on call blocking at your telco
- Signing up for a call blocking service like NoMoRoBo
- Setting up your own call blocker using open source software (Network Caller ID).
This article is a daily job that reports the effectiveness of these methods during the current month on my residential phone line.
Month to Date Call Blocking Effectiveness
Figure 1 shows the current month to date call blocking effectiveness for NCID for both calls on the FTC List and the black list from previous spam calls, as well as calls that are either blocked by NoMoRoBo or passed through as spam. There is really no good way to identify calls that NoMoRoBo stops. Valid calls are omitted.

Installation to Date Call Blocking Effectiveness
Figure 2 shows call blocking effectiveness for NCID from the date of installation. In early 2016, the phone line was ported from Verizon to a VOIP provider; this broke the NCID installation, but also made NoMoRoBo more effective by delaying the first ring to the VOIP phone. This delay allows NoMoRoBo to block many calls before the VOIP phone line rings. With the improved NoMoRoBo efficiency, there was not a strong incentive to fix the NCID installation, and thus the missing data for much of 2016. Although NoMoRoBo is effective at blocking calls at one ring, the peak of 37 calls in October, 2018 caused me to begin blocking repeat offenders with filters at VOIP provider; this immediately reduced the number of calls that ring even once.

Related Articles
For additional information, you may be interested in other articles on NCID and stopping phone spam:
- Stopping Rachel from Cardholder Services covers multiple ways to address phone spam, including setting up an NCID server.
- Download and Format the FTC Robocall Complaint List for NCID shows how to download and format the FTC complaint list to give you a list of spammers before they call you.
- Using NCID on Two Phone Lines shows how to add a second modem to your NCID configuration.
Updated Thursday, April 16 at 06:00 PM.