• New in CUCMv7
• Used by Smart Phones
• Allows users to place calls from Cisco Unified Mobile Communicator (CUMC)
• Similar to Mobile Voice Access on remote phones
• Calls made via Dial VIA Office will show corporate caller ID
• User can dial internal extension numbers and PSTN destinations
• The audio channel of the call, using the mobile voice network, can be set up by CUCM (like a reverse dialing)
  • User has the ability to choose any number to be used for reverse call (e.g. initiate a call from CUMC and select hotel number to be used for setting up the audio channel from CUCM to user)
  • Potential savings on toll charges and roaming charges
• The signaling uses GPRS for the data channel

• Dial-via-office with forward dialing
  • Mobile call is setup by mobile phone.
  • CUMC uses mobile data network to signal call.
  • CUMC user invokes dial-via-office feature on smart phone and calls directory number 2000.
  • Smart phone sends the call setup message over the mobile data network (GPRS)
  • CUCM informs the smart phone what PSTN number to dial to get dial-via-office access.
  • CUMC places the PSTN call over mobile voice network to dial-via-office number.
  • CUCM connects this incoming call to the target number (directory number 2000).
  • CUMC uses mobile data network (GPRS) to signal call.
• If the CUCM does not receive a PSTN call from mobile phone within 30s, the CUCM will send SIP Service unavailable to CUMC over data connection.

• SIP Invite from CUMC to CUCM over the data network
• Tell CUCM that forward dialing will be used

SDP parameter "a=setup:active"

• SIP Responds from CUCM to CUMC
• Indicates the number to be used for Dial-via-office access

SDP parameter "c=PSTN E164 5766711"

• Dial-via-office with reverse dialing
  • Call to mobile phone is set up by CUCM.
  • CUMC uses mobile data network to signal call.
  • CUMC user invokes dial-via-offce feature on smart phone and calls directory number 2000.
  • Smart phone sends call setup message over mobile data network and requests reverse dialing to its mobile PSTN number
  • CUCM places outgoing call to PSTN number of the smart phone.
  • When answered, CUCM connects the call to the target number (directory number 2000).

• SIP Invite from CUMC to CUCM over the data network
• First SDP tells CUCM that reverse dialing is requested
• Second SDP indicates the callback number to be used

SDP parameter "a=setup:passive"
SDP parameter "c=PSTN E164 4085551234"

• CUMC allows callback number to be set manually per call
  • Not limited to mobile PSTN of smart phone
  • Can be set to home landline number, hotel number, etc.
  • Call control (with enterprise features) is on CUMC, audio is on specified callback phone.