It wouldn't matter. The weakest link in any chain is the one that will be attacked. They'll simply listen in on the other end (the friend's phone), since the c

It wouldn't matter. The weakest link in any chain is the one that will be attacked. They'll simply listen in on the other end (the friend's phone), since the calls themselves are not encrypted and it is unlikely that the government is going to pay for all of his friends to have secure phones/lines. This has likely been the case with all calls to all friends of all Presidents for many decades.