Question about 3G network

[houndmommy]

I've had my bionic since November (before that I had a Blackberry, which I miss quite a bit) and I find I have many days where I can't get data.  So, is this a phone issue or a network issue?  I'm frustrated that I pay for data (plus bought an expensive phone) but can many times only use my phone as a phone.  Thanks for "educating" me on this.