[cisco-voip] SIP Trunk on CallManager Gateway Router

[O'Brien, Neil]

Hi,

 

A customer of mine has Call Manager 4.x and a few remote sites.  One of
the sites was connected via an MPLS network and had a PSTN connection on
their local gateway router.  They moved premises and ditched the MPLS
connection and instead of getting a new PSTN line, they went down the
SIP road and got a SIP trunk to an internet provider.  All the phones
continued to work via SRST to the local router and the router was
configured with the SIP trunk details as if it were a Call Manager
Express setup.

 

The remote site now has a VPN back to the HQ and the phones are now
registering back with Call Manager.  Their local gateway router is still
configured as that site's Call Manager H323 gateway and I thought that
once Call Manager pushed the calls to the gateway the call would
continue to go out over the SIP trunk.

 

Unfortunately, the SIP trunk only seems to register with the provider
when the phones register in SRST on the router.  When the phones
register back to call manager, the router will not register with the SIP
provider.  Outbound calls will still go out over the SIP but incoming
calls will not work.  I'm told by the provider that if the router isn't
registered with the SIP provider, outbound calls will still go over it
but inbound calls will not.

 

It's not a dial peer routing issue as when I debug the dial peers while
the phones are registered to Call Manager and make an inbound call I
don't see anything hit the router.  When the register in SRST, I see the
SIP calls come in and match the relevant dial peers.

 

I'm really at a loss as to why this would be, I don't know very well how
SIP works with Call Manager.  I'd really appreciate some pointers on
this...

 

Thanks for reading!!

 

Neil

 

 

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