For about a year our phones worked fine but I recently replaced the batteries with 1100 mAh because I could not obtain 600 mAh where I live. Now the screen produces messy characters and I cannot dial long-distance numbers without the phone turning off. In short, the phone is behaving strangely and I thought it was because of the batteries. I obtained new batteries of 650mAh but no change. Maybe I ruined the phones with the other batteries. Any ideas?