no ring or voice mail at all

So ive been trying to call a friend of mine for about 4 days now. When i do it doesnt ring at all. It doesnt even go into his voice mail. ive never had this problem before. its kinda like his number doesnt exist. but you would think that i would at least get a message about it from an operator. this happen to anyone or does anyone know why?

I have had this happen to me before.

I ended up calling the person's line back 20 mins later and just sat there with the phone to my head for like 5 minutes.

Eventually it began to ring.

Sometimes the signal doesn't make it all the way to the tower and it causes this effect. (at least that is how it was explained to me)

my phone will do that to me when the signal strength is low so im thinking thats what it is

It seems odd that you don't get voice mail at the very least.
Sounds to me like a network delay issue.
BlackBerry9530/4.7.0.65 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105