The magicjack is the issue here.
It is a VOIP device, which means it is transmitting telephone line data over a digital connection.
Faxes are analog devices and do not work over digital connections, the compression and encryption is not compatible.
Fax machines were designed for a normal copper based landline connection, and have difficulty working on even the highest quality digital lines. Magic ***** *****ne quality is very poor and virtually never compatible with faxing.
The one thing you can try is to go into the settings on your fax machine and find the send and receive (rx/tx) speed settings and lower those to the lowest option, and also to disable the error correction (ECM) feature.
Those 2 adjustments may help, if they do not, then your magic***** *****ne is not capable of working with the fax, which is a MJ limitation and cannot be otherwise overcome.
If you are needing to fax and don't want to subscribe to a landline, there are some other online faxing options such as efax.com for example, which will give you a fax number to use and send the incoming faxes to your email, and let you send outgoing faxes by scanning the documents and uploading through their service.
My apologies for the news.
If you have any other questions, just let me know. Otherwise, please take a moment to rate my service as this is the only way I am credited for my time. Hopefully I have earned 5 Stars but if not please let me know what I can do to ensure you are satisfied. I also invite you to contact me directly with any future support needs at http://bit.ly/1QwLxGh and ask for Nathan.
Thank you, ***** ***** a nice day,