iChat directional connectivity issues

Ok I have a wierd one here -

I have a macbookpro15 about 2 years old running OS 10.6.8 having a connection problem with video chatting with my fathers 2007 iMac running OS 10.6.8 also - I can send him a video chat request and it goes thru instantly when he accepts it. When he sends me a video chat request It does not go thru - here is the strange part - he just bought a 2011 macbookpro13 running OS 10.7.2 for my mom to use (grandkids video chatting) and it does the same thing !! I can send a vid request and establish a good link to HER - but when she sends me a vid request I either don't receive it or it times out waiting to establish. as a side note I am running a cable modem thru a airport extreme box at my house and my parents house is running DSL thru the airport express at theirs. we got together tonight to compare settings but i dont see anything in iChat that could be changed.....

if it was a two way problem, i would not be as perplexed - but the fact that it works perfectly so long AS I INITIATE THE CHAT makes NO sense to me...



anybody got any ideas??

thanks

more info

two things i forgot to mention in the original problem description:

1- we are using AIM screen names

2- this problem existed prior to the airport express being installed at my parents house - when they added the laptop recently they added the airport and the problem just extended to both computers - but the problem was there before they had the second computer or airport, which just has me scratchin my head......

thanks again !