[cisco-voip] SIP Question

[Andrew Dignan]

Howdy,

Here's an everyday question for you.

I have a customer that purchased LD/800 services from a company called
Masergy.  Masergy provides this service through a SIP Proxy Server made by
a company called Sonus Networks that is extended to the customer across
their MPLS network.  This is a centralized deployment with 12+ sites today
growing to 30+.  The customer is planning on taking in 800 calls and
distributing them across multiple callcenters across the country.  Remote
sites will use the Masergy LD service as a primary LD path, with rollover
to local PSTN connectivity at each site.  Wow...  Masergy is very vague on
how we integrate to them, uhh.. probably because they never have so It's
our job to figure it out for them(Glad the customer has deep pockets!!)

Here's some theories we've put together so far.

1)  Integrate CM to Masergy through a SIP trunk.  My understanding is that
SIP uses inband DTMF signaling and SCCP uses out-of-band thus requiring an
MTP resource for every SIP to SCCP call to meet at.  CM and the 6608 are
the only components I know of that can provide the MTP service.  This
customer has a single 6608 blade at the hub location where the CM are
located, so it's my understanding that every SIP/SCCP call would have to
go through the hub??  I think...  I've also read that 12.3(13)T supports
MTP with CM 4.0(2) and a future service pack, is it out?  don't know.  If
a router could be used as an MTP resource, then problem solved.  We'd just
need a DSP Farm at each remote site.

2) Configure H.323 on the GW's at each site(can't use MGCP because the
customer is doning t.37 off/on-ramp faxing) and a SIP dial peer into
Masergy's network.  Maybe this would resolve the need for MTP resources.

Anyone ever do anything like this?