Cannot redial an outbound number (one time works another doesn't) on U1911 using eSpace 7950 IP Phone.
Check office select code and office and prefix assignment. Found that on office select code 1 there are both SIP and AT0 trunks assigned for prefix 9. Check SIP peer device IP, it was used for other tests but forgot to delete it.
Solution: Delete the SIP trunk assigned to office select code 1 and problem solved.