I've bought Zoiper Premium on my Android 9 phone, Huawei Mate 10. The SiP account that I imported was Callcentric, which worked well on my other older Android 9 phone using Bria Mobile.
When trying to call most US or Canada mobile phone numbers in Zoiper Premium, I got "the phone number you have called is invalid or out of service". I only successed to call one US phone number.
Then after spending quite some hours, I found that I had to input the phone number manually from the key pad like 1626xxxxxxx. If choosing a number directly from the contatc list to call like +1 626-xxx-xxxx, it would not work. This is very inconveniant.
I guess that it might be that Zoiper Premium cannot interprete the phone number in the contact list correctly. What's the problem and how to fix?