try drinking PLENTY of water throughout the day. Ideally eight 8 ounce glasses of water is recommended daily. Hot tea is ok occasionally during the day but might dry your throat out some. You might also try asking your local Chemist/Pharmacist what they might recommend for using as a moisturizing gargle, something to add to gargle water. Maybe a Chamomille(sp?) or Aloe Vera type tea occasionally. I know you can buy in the US moisturizing throat sprays and professional speakers and singers have things they use to moisturizes their throats.
Plenty of water is the key though so drink it constantly throughout the day, even during the calls maybe with a straw to cut down on any gulping noises.
Hope this helps.
Mikala