I have a Samsung Galaxy S4 bought from Koodo November 2013. In the last few weeks I noticed when I place voice calls that sometimes when it connects to the Mobile network instead of the normal connection and the ringing sound as it rings the other parties phone I get a shrill fax machine sound coming out of my phone I have to hang up the call and redial again. Sometimes I have to do this a few times before the call goes through properly. Any ideas on this? Is it the phone? I still have warranty on the phone. Thanks in advance to anyone who has any ideas to resolve this. I love my s4.