Call Transfer between CCME systems

[cpartsenidis]

Hi everyone,

I've got a case where there are two CCME 4.0x systems where calls can be made between the systems using a h323 trunk.

I'm now trying to configure the systems so that when CCME1 accepts a call, the local operator can transfer the line to CCME2.

When I try to perform this, I get a beeping tone on the phone. My guess is that I haven't got the DSP farm configured, so I am unable to perform the transfer between the systems.

If someone can provide some information on what exactly needs to be done and any example configuration, it would be highly appreciated.

Thanks guys!

[bgrunewald]

Can you transfer calls internally?

To get basic transfer and conferencing you need to make the ephone-DN's "dual-line".

This works without DSPs from the "farm".

[Marwan ALshawi · Accepted solution]

With Cisco CME, you have three basic choices for the protocol used to support call transfer and forwarding for H.323 VoIP calls:

Standards-based H.450 Strongly recommended because it provides for optimal call paths and unlimited sequential transfers and forwards

Cisco-proprietary H.323 extension Mostly obsolete, but useful if you are using software older than Cisco IOS 12.2(15)T

Hairpin call routing Maximum compatibility but uses more WAN bandwidth and results in higher delay and jitter

try :

voice service voip

supplementary-service h450.12

allow-connections h323 to h323

telephony-service

transfer-system full-consult

transfer-pattern .T

also Transfers that use the blind mechanism work differently. In the blind transfer case, the transferor does not originate a consultation call. The initial call received by the transfer-to party in an H.450.2 transfer case by default has the transferee's phone number as the calling party. The transferee is often a phone number belonging to some external party. You are often not permitted to bill calls to this phone number even if you want to. Your PRI/BRI PSTN connection is very likely to reject any outbound calls that attempt to claim an external number as the calling party identifier.

To force hairpin VoIP call routing, you can switch on H.450.12 services on your Cisco CME router and use a separate PSTN gateway router on which H.450.12 is disabled (or not supported). Alternatively, you can explicitly turn off H.450.2 service on your Cisco CME voice dial peers that route calls to the PSTN gateway router. You do this using the no supplementary-service h450.2 command

example:

dial-peer voice 100 voip

destination-pattern 9.T

session target ipv4:10.0.1.20

no supplementary-service h450.2

source cisco press

good luck

please, if helpful Rate