1. A method for communicating using an I1 interface, the I1 interface providing a session control channel, the method comprising: identifying a session initiation protocol (SIP) encoded message; determining whether the SIP encoded message is to be transmitted using the I1 interface; in response to determining that the SIP encoded message is to be transmitted using the I1 interface and the SIP encoded message is larger than a maximum payload of the I1 interface, reducing a size of the SIP encoded message by: identifying a first string to be transmitted in a first information element of the SIP encoded message to at least one of a user agent (UA) and a network node, the first information element of the SIP encoded message including at least one of a uniform resource identifier (URI), a Public User Identity and a SIP UA capability; identifying a synchronization table associated with the at least one of the UA and the network node; using the synchronization table to identify a first key associated with the first string and the first information element of the SIP encoded message; and when the first key associated with the first string and the first information element of the SIP encoded message is identified in the synchronization table: encoding the first key within the first information element of the SIP encoded message instead of the first string, and transmitting the SIP encoded message to the at least one of the UA and the network node using the I1 interface; and in response to determining that the SIP encoded message is not to be transmitted using the I1 interface, not reducing the size of the SIP encoded message.