overlap receiving and sending

ciscoforum · ‎06-19-2007

The following is from Cisco 5.x SRND about the overlap sending and receiving

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a00806375f2.html

Overlap Sending and Overlap Receiving

In countries whose national numbering plan is not easily defined with static route patterns, you can configure Cisco Unified CallManager for overlap sending and overlap receiving.

Overlap sending means that Cisco Unified CallManager keeps collecting digits as they are dialed by the end users, and passes them on to the PSTN as they are dialed. To enable overlap sending in Cisco Unified CallManager Release 4.0 or later, check the Allow Overlap Sending box on the Route Pattern Configuration page. (In earlier Cisco Unified CallManager releases, overlap sending is enabled by setting the SendingCompleteIndicator service parameter to False.) The route pattern needs only to include the PSTN access code (for example, "9." in North America or "0." in many European countries).

I still not clear even after reading this, can anybody give me an example how this is achieved. I haven't seen this useful at least in U.S. Thanks

mchandak · ‎06-19-2007

In US, it only depends on the Telco. There are some Telco's who might not have the capacity to handle the numbers sent in enbloc and therefore need it with Overlap Send. I've also not seen it being used most of the time in US, except for some old CAS links. Dont remember seeing this with a T1-PRI.

This plays an important role in countries in Europe and Asia. There could be some countries which have a different number based on the city. Some might be a 5 digit number and some 6-7 digit numbers and there Telco's prefer using Overlap Send, where the Calling network/device sends a setup with a few digits in the setup and then one digit at a time. When they sending equipment has completed the calling party number, it sends a Setup Complete, letting the other end know that it would not be sending anymore digits and the call should be processed based on the all the digits sent.

Using Overlap Send/Receive normally depends on how the Telco would like to receive/send digits.

Hope this helps

ciscoforum · ‎06-19-2007

Thanks very much for your reply.

Could you elaborate a little more with an example? What I don't understand yet is about the overlap. what does the overlap specifically mean? Does it mean as you mentioned in Asia, one city's E164 number is 571-xxxxxx(571 is the area code), the other city could be 57-xxxxxx(57 is ared code), is this kind of overlap? THanks

thisisshanky · ‎06-19-2007

Check this isdn sample trace to understand how OSR works.

Overlap send receive is used in certain countries like Germany. Overlap send receive is supported in QSIG based switch types.

To setup OSR, add a route pattern 9. with Allow Overlap Sending enabled. Select the qsig gateway that you added (6608, mgcp t1 gateway etc). When OSR is enabled, FAC and CMC are automatically disabled.

Debug isdn q931 will look like this. The number dialed is 2142142142. I have set this up in a lab and a PSTN simulator router was ued. The simulator router, waits for each digit to come by and then routes the call. Make sure on the PSTN router the following command is enabled.

interface Serial1/0/0:23

no ip address

isdn switch-type primary-qsig

isdn overlap-receiving

isdn protocol-emulate network

isdn incoming-voice voice

no cdp enable

Jun 15 02:01:24.129: ISDN Se1/0/0:23 Q931: RX <- SETUP pd = 8 callref = 0?0001

Bearer Capability i = 0?8090A2

Standard = CCITT

Transfer Capability = Speech

Transfer Mode = Circuit

Transfer Rate = 64 kbit/s

Channel ID i = 0xA98384

Exclusive, Channel 4

Facility i = 0?9FAA06800100820100A11A020101020100801253796C7665737465722

05374616C6C6F6E65

Calling Party Number i = 0?0081, '5003'

Plan:Unknown, Type:Unknown

Called Party Number i = 0?80, '2' Plan:Unknown, Type:Unknown Jun 15 02:01:24.133: ISDN Se1/0/0:23 Q931: TX -> SETUP_ACK pd = 8 callref = 0?8

001

Channel ID i = 0xA98384

Exclusive, Channel 4

Jun 15 02:01:24.885: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '1'

Plan:Unknown, Type:Unknown

Jun 15 02:01:25.497: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '4'

Plan:Unknown, Type:Unknown

Jun 15 02:01:26.089: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '2'

Plan:Unknown, Type:Unknown

Jun 15 02:01:26.673: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '1'

Plan:Unknown, Type:Unknown

Jun 15 02:01:27.217: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '4'

Plan:Unknown, Type:Unknown

Jun 15 02:01:27.793: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '2'

Plan:Unknown, Type:Unknown

Jun 15 02:01:28.493: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '1'

Plan:Unknown, Type:Unknown

Jun 15 02:01:29.013: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '4'

Plan:Unknown, Type:Unknown

Jun 15 02:01:29.601: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '2'

Plan:Unknown, Type:Unknown

Jun 15 02:01:30.173: ISDN Se1/0/0:23 Q931: RX <- INFORMATION pd = 8 callref = 0

x0001

Called Party Number i = 0?80, '9'

Plan:Unknown, Type:Unknown

HTH

Sankar

PS: please remember to rate posts!

Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus

ciscoforum · ‎06-20-2007

Hi Sankar

Thanks for your spent time in the lab to verify this. Here are my more questions:

1. Did you use MGCP Qsig or H323 Qisg in the lab?

2. When you dial, did you dial 2142142142 or 92142142142?

3. If you dial 92142142142, then it matchs the route pattern you created whcih is 9. ? right?

4. I did see the debug and it shows 1 digit by 1, not like we know the entire called number sent in the Q931 as usual. But what the benefit to be this way? I still not clear about that, what does this achieve by sending digit one by one?

Thanks