angryciscoguy

While SRST has it’s place, it limits are easily found. A while back Cisco introduced a new feature to CME that allows it to perform SRST functions with the added features that CME provides. I recently tried this configuration out myself and was pleasantly pleased in it’s performance. Check out the details for yourself here:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/guide/cmesrst.html#wp1015579

I chose to use the setup where the CME “learns” the config of the phones similar to how normal SRST works. A “gotcha” with this (that got me… >:8 grrr)  was the restriction that you dont save your IOS configuration while in fallback mode. And yes, it is documented… The reason for this is due to the way CME-as-SRST handles it’s ephones and ephone-dn’s. In a normal SRST setup you will nto see these in the config, however in the CME-as-SRST setup you will, but only during fallback. If you save the config you are essentially staticly configuring those phones and the system can no longer learn the configuration during the next fallback. The symtoms present themselves as phones that seem to revert to old configuration when fallback is operational. The fix is to delete all the learned ephones and ephone-dn’s while the system in not in fallback mode and then “write mem”.

At times it is not necessary for voicemail boxes or advaced auto-attendant features on a remote gateway that is serving a small office. This is especially true for remote non DID (ie FXO trunked) SRST gateways that are only active a small amount of time. Instead of adding a AIM-CUE or NM-CUE voicemail module in the gateway, basic auto attendant features can be provided right in IOS. (more…)