Texting issues between Droids and iPhones?

So I have the Droid Razr on the Verizon Wireless network. The people I am mostly texting throughout the day have iPhone (4 and 4s same network). Now when I am texting them some messages aren't getting through to them, I have delivery reports on to see if it was getting sent or not and a lot of them stay in "Pending". This happens with no other phones or networks. They all go through regardless except on the iPhones. Even if the texts are short they still don't get through. Any idea on how to fix this? I already tried the factory reset and tried a different messaging app ( I know it wouldn't make a difference just had hope.) So what's the fix?

That was most probably I'm also thinking on gettina a messaging app or reset your unit but nevertheless all doesn't seem to get the right solution.

It's better to inform you're mobile carrier on why does it stay on pending and maybe they could help you in some way.