ip phone 303 when forwarding to an external phone number, call goes straight to voicemail

[wmtr]

Hi all,

Have a question here: so we have a cisco ip phone model 303. When we set the forwarding all to an external number(instead of putting 10 digits number at default, we must add 1 in the front to properly dial otherwise it says number doesn't exist, this is a problem on its own, not sure if related to the forwarding one), the caller will here exact two rings then it goes into voice mail. The destination number will not see any incoming call at all.

Does anyone know what's causing this to happen and how to fix it?

Thanks!

[Flo.Matalis]

1. Does this happen to only 1 external number only?
2. Can you try to forward it to another internal number? and external number?
3. If you dial the number directly from other phone, what do you get?