From what I remember, they mailed me some forms to fill out and return to them. They requested lots of medical records which they got from my doctor. I suspect they want to see visual tests already established and the dates. "Eventually", I received a letter from them requesting me to travel to one of their testing facilities. At the test center they performed whatever was requested. You leave knowing nothing but they do pay for some travel expenses.
Not sure how long it took for them to write back that I was accepted int the club and explain the details.
I suspect the reason for the phone calls and voicemail is based on them all working from home. All I can suggest is to keep calling and leaving messages with how many times you did it previously without a response. Everything moves very slowly. Once they establish a date you will be paid for past months benefits all in a lump sum. You may wish to have them take out some Federal witholding tax or you might get hit with an unexpected tax bill the next time you file.
Just be patient and keep copies of everything you send them in case you need it in the future.

It is a complicated process to apply for disability benefits. I applied in April, was declared legally blind in May, and was approved in late July. I got my first benefits in December. I was 38 at the time I applied. My biggest suggestion is to obtain your own medical records and take them to the local Social Security office. Most of the time in adjucating disability claims is the employee waiting on sufficient records to make a decision. Good luck and best wishes!