The update released on July 16th has fixed my "Silent Call" issue thus far. So please be patient as you will get the OTA MR4 soon. It may take a week before the whole customer base has the update but you WILL get it.
I installed the update the day they started rolling out the update (July 16th) and as of today (July 18), I have had no issues with silent calls yet. So I will keep my fingers crossed and hope this will fix it for good.
If you haven't yet got the update on your Eris and cannot wait any longer, the OTC update is here on the Google servers for you to download and install manually.