this is the problem: the upload speed. if you have any music download app or program installed on your pc or cell phone then what happens is that when your cell phone is on or the laptop is turned on, it begins to upload files automatically, thus eating up the limited upload speed you have, this will cause your voice sound choppy to the other person. in any case, both your upload speed and download speed are at borderline line. I thought no one gets this slow plan anymore as its worth almost nothing for anything usable these days. I am also sure you have other people or devices connected to this wifi router. if anyone is using the net for anything or has the music / movie download program installed then you will get bad call quality. I have a 45mb download and 5 mb upload speeds. you can pretty much do anything in my wifi and I will still get great call quality.
My calls are all to and from USA so I only use google voice. its all free and I have been using it as my american line for as few years now, all free.
I use a linksys pap2 voip internet phone adapter which is configured to a free voip account with free american DID number: callcentric. so now I get free incoming calls to a hardline at home as well. I simply use my google voice number to make and receive calls. I use groove ip to receive and make calls via cell phone, using google voice. I have not paid a cent for many years to call usa. why get vonage and magicjack when google voice gives you all for free?
AZB