From chapter on using an iPhone as a … telephone.
When telephone calls migrated from mechanical switches to digital networks they picked up an unexpected problem. It’s now quite easy for someone outside of the US legal system to phone someone in the US with a fake phone number. These calls are used for everything from advertising to scams to stealing people’s identity and money. An unlisted number is of little help, digital dialers call phone numbers randomly 1 as well as lists of known active numbers. Many of us no longer answer any calls with an unrecognized Caller ID 2.
Explorers may be particularly vulnerable to exploitation of course. So it’s a good idea to consider defensive options.
To start with an Explorer’s number should be added to Federal Do Not Call registries at https://www.donotcall.gov/register/reg.asp. This has only a small effect on modern spam but It’s a reasonable start.
Some mobile carriers are implementing defenses against spam calls. They use proprietary rules to try to distinguish good and bad calls 3. If your Explorer’s carrier provides phone filtering I recommend enabling this feature 4. I’ve used AT&T Call Protect with good results. As of the time I write this AT&T and Tmobile provide call blocking for free, Sprite and Verizon charge for it.
The iPhone also supports “Call Blocking & Identification” either by adding Blocked Contacts 5 or using a Call Blocking & Authentication service 6.
The Do Not Disturb feature is another option to consider. An iPhone can be setup to silence all incoming calls and messages unless they match a Contact. In Settings:Do Not Disturb set Silence to “Always” and Allow Calls From to “All Contacts”. I have seen problems with this setting however, in some versions of iOS it blocks Message.app notifications even for people in Contacts. This is a bug that may be fixed by the time you read this.
The best defense against phone spam at this time is a Carrier service and Explorer education. Using Call Blocking & Identification or Do Not Disturb features can work for some but are tricky to manage.
1 In any given US area code there are at most 9,999,999 phone numbers and many mobile numbers are reused.
2 In theory a spam call’s fake number might, by chance, match a number in Contacts. I have thousands of Contacts though, and I’ve never seen this happen. Ignoring unrecognized calls isn’t an option for everyone unfortunately.
3 These products can help reduce attacks but won’t get everything.
Carriers are also looking into next-generation communication systems that authenticate callers and can use the same approaches that manage email spam. This may be 5-10 years away though.
4 Alas, I need to make some privacy warnings here. This product gives AT&T access to user Contacts. I don’t know what privacy policies are in place.
AT&T Call Connect is based on a product called HiYa. It’s “free” because the vendor sells user information to marketers. It would be funny if robocallers were buyers!
5 One trick: Create a Contact called “Bad People” add add numbers to it. Then block “Bad People”.
6 See Apple support: https://support.apple.com/en-us/HT207099. I can’t recommend a specific service however.