Issue with ConnectionService PhoneAccount registering in android

Question

I am trying to use Twilio for video calling application, one end is web and another end is android. Using Firebase to trigger push notification from web to android. I need to convert the push notification as Incoming call screen in android application, to do that I have used ConnectionService which is documented as available from API 23. I have registered PhoneAccount as below:

TelecomManager tm = (TelecomManager) getSystemService(Context.TELECOM_SERVICE); 
PhoneAccountHandle phoneAccountHandle = new PhoneAccountHandle(
                new ComponentName(this.getApplicationContext(), MyConnectionService.class),
                "AppName");
PhoneAccount phoneAccount = PhoneAccount.builder(phoneAccountHandle, "AppName")
    .setCapabilities(PhoneAccount.CAPABILITY_CONNECTION_MANAGER).build();
    tm.registerPhoneAccount(phoneAccount);

I registered PhoneAccount for first time with

PhoneAccount phoneAccount = PhoneAccount.builder(phoneAccountHandle, "AppName")
  .setCapabilities(PhoneAccount.CAPABILITY_SELF_MANAGED).build();

which will work only on API 26, Later I changed it to

PhoneAccount phoneAccount = PhoneAccount.builder(phoneAccountHandle, "AppName")
.setCapabilities(PhoneAccount.CAPABILITY_CONNECTION_MANAGER).build(); 

Later one worked as expected in API 26 but on lower versions, it gave an exception

java.lang.SecurityException: This PhoneAccountHandle is not registered for this user!

can anybody help with this issue?