Verizon router MI424WR conflict with voice over IP

[#1]

I was recently as of Jan 6, 2009 set up with FIOS.  In my network of computers and printers I also have a linksys T-mobile router with voice over IP (voIP).  Very shortly after installing FIOS all was well until just recently (about 1 week ago) I started to experience a problem with the voIP.  I get a dial tone and can call out however I can not hear the party's phone ringing and can not hear them talking.  They can hear me talk. 

I have the original firmware on the Linksys router.  I was told that Verizon has done a firmware upgrade but can not give me the previous firmware. 

Are there any suggestions for me to help getting my phone working?

[#2]

Well, I have never come across this issue before, but it sounds like a quality of service issue and not really a port issue of any sort so I doubt opening any type of port will fix anything. If your ONT allows it, try bypassing our router with the linksys and see if the problem is fixed.  Just want to verify it is the actiontech router causing the issue...

[#3]

Yes it is an Actiontec.  The router is also the modem and as far as I know would not be able to put the TM-router on the other side.

[#4]

There is no modem with FIOS.

[#5]

OK on the modem.

What do you mean by "If your ONT allows it, try bypassing our router with the linksys and see if the problem is fixed."