E1 line code and framing mode

For E1 trunks, the line coding is always HDB3 (high-density bipolar of order 3). This is similar to B8ZS. No system parameter needs to be set.

The E1 Framing Mode parameter (in the Trunk Interface parameter group) should be set to the correct value, as shown in Table 1. The possible values are:

Double

Double Frame has two concatenated frames (this is the default.)

CRC

CRC, or multiframe, has 16 concatenated frames. This type of framing also has cyclic redundancy checking and is recommended for ISDN connections.

Table 1. E1 Framing mode values for different signaling protocols.

This table describes the correct value of the E1 Framing Mode parameter to use for Channel Associated Signaling and Common Channel Signaling with different protocols and countries or regions.

Signaling Mode	Protocol	Country or region	E1 Framing Mode
Channel Associated Signaling (CAS)	All	All	Double
Common Channel Signaling (CCS)	ISDN	All	CRC
	Other	All	Double