On old SIP system or forgotten SIP-specific credentials?
Chat with xmpp:cheogram.com in your XMPP client and say reset sip account to register with the new username (all numbers, no "~")
When configuring linphone use:
Username: (all digits, provided by the chat bot) Password: (the SIP-specific password provided by the bot, 3 words including spaces) Domain: jmp.cbcbc7.auth.bandwidth.com:5008 Transport: UDP
For an example screenshot see: attachment:linphone-assistant-setup.jpg
