Have a OS 100 and adding ext 254. Trying to program in 722 but not allowed. I can dial out using 701, 702 ect.. intercom ok.

what about key programming in MMC107 on extension 254 itself?

Did you add the extension in the numbering plan or was it already there? Does the 254 show up on the phones display?

Hof - did not try MMC 107, but i will

pvj - I did add the ext. - 254 does show up in display now.

107 i only going to let you add extenders not fully program keys.
Make sure you are under Tenant 1 when going into programming