I'm testing with my family member's phones.
When my grandma(Verizon) calls my skype online number (425-440-xxxx), there is ringing animation on the cell phone lcd with no ringing sound for about 2 seconds and just stopped.
When my aunt(AT&T) and my cousin(Verizon) calls my skype online number (425-440-xxxx), it works as it should be.
Also, couple of my customers complained that call just dropped like my grandma's case.
Any age discrimination? Sorry didn't ask my customer's age.