both you and your friend are using the mobile phone service of the
same wireless network operator, the transmission of an SMS message
from you to your friend will involve only one wireless network
operator. This SMS message is called an intra-operator SMS message.
the cost for sending an intra-operator SMS message from a mobile
phone is lower than that for sending other kinds of SMS messages such
as inter-operator SMS messages. Some wireless network operators allow
their subscribers to send unlimited intra-operator SMS messages free
Process of Intra-operator SMS Messages
transmission of an intra-operator SMS message involves only one SMS
center. After leaving the sender, the intra-operator SMS message
reaches the SMS center. The SMS center then delivers the SMS message
to the recipient mobile phone. If the recipient mobile phone is
offline, the SMS center stores the SMS message. It will deliver the
SMS message when the recipient mobile phone is online. If the SMS
message's validity period expires and the recipient mobile phone is
still offline, the SMS center will remove the SMS message.
the SMS center receives the message delivery report from the
recipient mobile phone or removes the SMS message (for example, when
the validity period expires), it sends a status report to the sender
if the sender requested one earlier.
following figure illustrates the transmission process of an
intra-operator SMS message: