Sometimes some ip phones can't make outgoing calls to another ip phone or PSTN ,i have to remove Directory Number from ip phone and add again.
Anyone have experienced this?
Unfortunately, You did not mention the model numbers of the IP phones.Please include this information in your post
I'm experiencing the same issue with 7912 phones and the 5.0(0) phone load shipped with CCM4.1(2)sr1.
I've just tried to upgrade to phone load 6.0(0) (CP7912060000SCCP050124A.sbin). Unfortunately, with this load the phones don't boot anymore... So, I had to roll back to 5.0(0) again.
For this issue I'm going to open a TAC Case now...
With phone load 6.1(0) the 7912 phones finally run stable for about three weeks now.
With phone load 6.0(0) we were running into Bug ID CSCsa72417 ('Cisco IP Phone 7912G dies when configuring Graphics via TFTP on CCM 4.1'). On our implementation we're using the company logo instead of the Cisco logo. This issue has been solved in 6.1(0) version.
With version 6.1(0) also the problem with outgoing calls seems to be solved.
Hope this helps.