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Newbie to IP Telephony

I'm new to IP telephony and I need a voice solution. My organisation has like 15 offices, all linked together. What I need is a cost effective way of implementing the voice solution. Considering the small number of branches we have, will using a call manager be worth it?. Some of the lcations have existing PABX systems, and it is desired that at these locations, these extensions should be able to call anybody. At locations without a PABX, 1, 2 or 4 extensions might be required.

I would appreciate a link, a design, a summary or a tip to get going on this solution.



Re: Newbie to IP Telephony

Sounds like Call Manager Express (CME) would be a good solution. This is based on a IOS router and has IP phones across the LAN. Have a look here for more information -


Re: Newbie to IP Telephony

Thanks, but the documentation of the CME mentions that it can only be used on the LAN (and not across WAN links as in my case). Is this because of the DHCP required by the IP Phones?. If so, can I possibly set static IP addresses on the IP phones and hence beat this limitation. Or what is a workaround.

Thank you.


Re: Newbie to IP Telephony

At this stage, ITS does not support G729 (low bit rate codecs) so spreading all the phones across the WAN would be a bit of a problem as you would be forced to use G711 codecs. The ITS handsets assume they have full LAN B/W but if there is enough B/W across the WAN then there is nothing stopping you do this.

Another solution could be to use ITS at each of the larger sites where you have multiple phones - this would give you normal telephone system features. If you have sites with one or 2 handsets you could use something like an ATA or FXS ports on the router and set up a meshed network of VOIP or POTS dial peers. A H323 gatekeeper could also be used to allow the network to scale up to larger numbers of sites and keep the configs simple.