Hi Ankit,
Line Anoop said, there is no limitation set in CUCM code but there are some consideration
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab09/clb09/netstruc.html
Considerations for Shared Line Appearances
Calls placed to shared line appearances, or calls sent to line groups using the Broadcast distribution algorithm, have two net effects on the bandwidth consumed by the system:
•
Because all the phones on which the line is configured ring simultaneously, they represent a load on the system corresponding to a much higher calls-per-hour (CH) value than the CH of the line. The corresponding bandwidth consumption is therefore increased. The network infrastructure's bandwidth provisioning requires adjustments when WAN-connected shared line functionality is deployed. The CH value employed for Equations 3 and 4 must be increased according to the following formula:
CHS = CHL * (Number line appearances) / (Number of lines)
Where CHS is the shared-line calls per hour to be used in Equations 3 and 4, and CHL is the calls-per-hour rating of the line. For example, if a site is configured with 5 lines making an average of 6 calls per hour but 2 of those lines are shared across 4 different phones, then:
Number of lines = 5
Number of line appearances = (2 lines appear on 4 phones, and 3 lines appear on only one phone) = (2*4) + 3 = 11 line appearances
CHL = 6
CHS = 6 * (11 / 5) = 13.2
•Because each of the ringing phones requires a separate signaling control stream, the quantity of packets sent from Unified CM to the same branch is increased in linear proportion to the quantity of phones ringing. Because Unified CM is attached to the network through a 100 Mbps interface, it can instantaneously generate a very large quantity of packets that must be buffered while the queuing mechanism is servicing the signaling traffic. The servicing speed is limited by the WAN interface's effective information transfer speed, which is typically two orders of magnitude smaller than 100 Mbps.
This traffic may overwhelm the queue depth of the central site's WAN router. By default, the queue depth available for each of the classes of traffic in Cisco IOS is 64. In order to prevent any packets from being dropped before they are queued for the WAN interface, you must ensure that the signaling queue's depth is sized to hold all the packets from at least one full shared-line event for each shared-line phone. Avoiding drops is paramount in ensuring that the call does not create a race condition where dropped packets are retransmitted, causing system response times to suffer.
Therefore, the quantity of packets required to operate shared-line phones is as follows:
–SCCP protocol: 13 packets per shared-line phone
–SIP protocol: 11 packets per shared-line phone
For example, with SCCP and with 6 phones sharing the same line, the queue depth for the signaling class of traffic must be adjusted to a minimum of 78. Table 3-12 provides recommended queue depths based on the quantity of shared line appearances within a branch site.
Shared lines also consume CPU resources. Not only do shared lines count as extra lines on the phones that share DNs, but each call from or to any of the shared line phones is reflected on all of the other phones as well.
(Rate if it helps)
JB
