RTD Delay- Design question

[iptuser]

There is a recommended min. 150 RTD for voice but is there a min. for call control. I`m thinking of deploying SRST cluster but only send Call Control across the Link with local telco traffic via a local T1. All IPT calls will either be on the same router so no WAN traffic except Call Control or via the E1. There may be a local CUE or not

thanks

 

[whykap]

What about calls between sites? They will not be calling between sites?

Anyway the 150ms is the maximum and not the minimum. And it is roundtrip, not one way, at all times.

Call control does not have a 150ms requirement but you need to give it priority over other traffic using QoS. Otherwise you will have call control delays and all kinds of weird issues.

 

[iptuser]

thanks for the reply

The idea is that the links between the sites are low Bandwidth and the cost to upgrade to add voice may be too much so we are thinking of running call control only with all other call out via the local telco. Is there any paper/ document which I can be pointed to. Some of the links are VSAT so again the delay for voice may be too much but for call control??????.

You are correct it is one way but technically you can go beyond the 150 ms - the 150 mark is the recommneded for toll quality but it depends on what you can risk

 

[whykap]

Yes the SRND for the call manager version version you are running will give you the details. If you can't find it I can send you the link next time I get a chance.

Technically you can go beyond 150ms, but your voice quality will suffer. With a sattelite connection you wont get anywhere close to 150ms. which means you will have users telling you this phone system sucks and CISCO is crap.

Do it right or don't do it at all. That's my recommendation. That is why there are specs for every technology.

 

[iptuser]

Can anyone provide any more info. - Is the 150 ms limit also for Call Control?