Voices breaking up in headset

[Sopman]

I'm using a Robotics 56K external modem, Netzero has my ISP and connecting up at 26400. Yeah, I know, not much I can do. Anyway, while in Yahoo messenger the sound is breaking up. Is this because of my internet connecting or is their a remote possibility that the sound card could be doing this??
I know my sound card is probably bottom of the line, since I bought my computer at a computer fair.

 

[StarTAC]

the cause in breakage is most likely because of the amount of bandwidth u have from your provider.. u might wanna get up to 56Kbps or even 64Kbps, to experience better sound quality......

good luck..