FreePhoneLine configured

I have FreePhoneLine configured for over a year, I use it as a failover of service. I did have issues but I have found these to be reliable:

RegistrationPeriod : 360
DigitMap:   (*98|1xxxxxxxxxx|<1>[2-9]xxxxxxxxx|xx.|(Mipd)|[^*#]@@.)

I changed the following settings according to freephoneline requirements, although the previous settings had worked fine since the beginning:

Registration Period: 3600
Registration expiry: was already 3600
Failed Registration Retry: 120

Rest left at defaults. I added the *98 for voicemail and it seems to work pretty good.