Other Nokia N900 tips

To setup diamondcard.us SIP service for use with Nokia N900's SIP telephony, use the following way to set it up:

Open up your address book, then personal info, and accounts. Setup a new SIP account:

User name XXXXXX@sip.diamondcard.us (where XXXXXX is your diamondcard.us ID)
Password ******** (your diamondcard.us PIN)
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Advanced options
Use for telephone numbers ticked
User name XXXXXX (where XXXXXX is your diamondcard.us ID)
Transport UDP
Outbound proxy sip.diamondcard.us
Port 5060
Discover public address ticked
Loose routing ticked
Keep-alive mechanism Auto
Keep-alive period Auto
Auto-detect STUN ticked

Having it set up this way I can make SIP calls through diamondcard.us on the Nokia N900 GNU mobile phone.