I have always been able to dial SIP URI's from my SPA504G directly registered with various VoIP providers that I use.
That is, until I upgraded from firmware version 7.4.7 to version 7.4.8.
For the last few days I couldn't figure out why I was no longer able to dial direct SIP URI's (using contact list).
Then, I remembered I upgraded earlier this week from ver. 7.4.7 to ver. 7.4.8.
This morning I reburned version 7.4.8 just to be sure the upgrade was clean. No help.
Then, I down-graded back to version 7.4.7..... Now, URI dialing works just fine.
Sounds like a problem with version 7.4.8 to me.
Anyone else try this?