We would like to use the SNR feature on the UC520, but it takes way too many rings before the mobile gets its first ring, by that time the customer will have probably given up.
With SNR enabled I place a call from an external line. After a couple rings my handset starts ringing, but it takes another 2 rings before my mobile phone starts to ring.
I take your point about the delay, and agree it is not ideal. Just to break it down a little so you can see where it is coming from:
1. Two rings to detect CLID before extending the call to the desk phone and SNR
2. Maybe a second to dial the phone number out the analog trunk
3. Setup time in the PSTN before the remote phone rings
#1 is specific to analog trunks, since we get CLID information in between the first and second ring. The use of a ditital line such as ISDN or SIP will eliminate this. There is also a CLI command that will make the desk phone ring immediately we detect the call, but you won't see CLID on the phone until a few seconds later once we have collected it from the PSTN. This can be confusing for some people, which is why we default to suppressing the call until we have the CLID.
#2 again is specific to analog trunks, but should not be more than a second depending on the number of digits to be dialled.
#3 is a bit unpredictable, but I'm surprised it is taking as long as it is when calling a land line. Can you capture the output of 'debug vpm signal' again, but make sure you enable timestamping of debug messages by first configuring 'service timestamps debug datetime msec localtime' before reproducing. But there may not be anything we can do about this. Once the trunk has been siezed and the number dialed, we are at the mercy of the PSTN.
The additional time take between when the desk phone starts to ring and the mobile starts to ring is at least in part due to the delay parameter that is set on the snr command. The delay is exactly what it sounds like - the length of time between when the call is received at the UC500 (essentially when the desk phone starts ringing) and when the UC500 extends the call out to the mobile phone. It is set to a five seconds delay in your config, which, when added to the initial delay for the UC500 to detect CLID, works out to the five or six rings you are seeing.