Information About Integrating Voicemail with Cisco Unified SRST
Cisco Unified SRST can send and receive voicemail messages from Cisco Unity and other voicemail systems during Cisco Unified CM fallback. When the WAN is down, a voicemail system with BRI or PRI access to the Cisco Unified SRST system uses ISDN signaling (see figure Cisco Unified Communications Manager Fallback with BRI or PRI). Systems with Foreign Exchange Office (FXO) or Foreign Exchange Station (FXS) access connect to a PSTN and use in-band dual tone multifrequency (DTMF) signaling (see figure Cisco Unified Communications Manager Fallback with PSTN).
From Unified SRST Release 12.0 onwards, Unified SRST supports voicemail on IPv6 protocols for SIP IP phones.
Both configurations allow phone message buttons to remain active and calls to busy or unanswered numbers to be forwarded to the dialed numbers’ mailboxes.
Calls that reach a busy signal, calls that are unanswered, and calls made by pressing the message button are forwarded to the voicemail system. To make this happen, you must configure access from the dial peers to the voicemail system and establish routing to the voicemail system for busy and unanswered calls and for message buttons.
If the voicemail system is accessed over FXO or FXS, you must configure instructions (DTMF patterns) for the voicemail system so that it can access the correct voicemail system mailbox. If your voicemail system is accessed over BRI or PRI, no instructions are necessary because the voicemail system can log in to the calling phone’s mailbox directly.