The Telebroad voicepad is their own version of a VoIP Softphone. According to the Telebroad Cloud PBX requirements, they use compressed audio on their voice channels for which your actual bandwidth should be more than enough (a uncompressed Audio channel would use around 100 KB/s and a compressed channel uses about the half, so your speed should have you covered.
If your Telebroad VoicePad or Voip softphone hangs up on you in middle of a call, perhaps you may be using a poor wireless connection from your laptop to your Modem or you may be moving away from it?
If that's not the case, since you're actually using Telebroad as your phone provider too, I recommend that you call their support line.
Hope that helps.