They are allowed to have any requirements that they want. The phone recording system that SASSIE uses displays the phone number that you are using, and some shops explicitly say that the area code you are using needs to match the area code of the merchant you are calling. Getting a burner number for each new area code takes time, and might not be worth doing for a low-paying phone shop. I have seen some that say you either need to live there or be familiar with the area due to the questions they expect that you might be asked. There is no "one size fits all" answer to your question about whether you can do phone shops from anywhere.
I have randomly been asked for my zip code, asked about my reaction to local weather conditions, and have been asked which high school I attended. All totally random stuff. I generally do a quick Google search for the weather any time that I am calling out of my area. I also look at a map. Often, the smaller the town, the more likely I that "local" information will come up as part of the conversation.
I received a email the other day from IPSOS for a phone shop..
I know that on most of them, you can do them from anywhere but you may need to create a second email address /and on phone number.
I e-mailed and asked for a little more information and they said that I have to live in the same state to do the shop.
I looked (About 500 miles away) and I did not see any listed (Unless they were all taken )
I thought you could do phone shops from any where?
Shopping Southeast Pennsylvania, Delaware above the canal, and southwestern NJ since 2008