New SIP trunk, can't hear called number ring, everything else fine

[wilson_1234_2]

We are in the process of testing a new SIP trunk.

The Gateway is configured IP2IP Gateway.

The insbound and outbound calling seems to be working fine, but when I dial an outside number, I do not hear the remote end ring.

When the remote end picks up, I hear everything fine.

Inbound calling seems to work fine.

Would this be a carrier issue, or Gateway config?

Is there a way for me to debug the Gateway and determine where the issue is?

[Nicholas Matthews]

Hi Wilson,

There are few things you can do to try to fix this problem. There aren't any details, so this is speculation:

voice service voip

h323

emptycapability

sip

midcall-signaling

On CUCM:

If H323 gateway:

Check 'MTP required'

Uncheck 'wait for far-end H245'

Enable outbound fast-start

Enable inbound fast-start

If SIP gateway:

Check 'MTP required'

What is probably happening is you're doing slow start or late media out, and your provider is sending in-band ringback. They should be sending a 180 Ringing, or we will need to send early media. That's what this configuration should help with.

hth,

nick