ISDN_P_BASE		0
ISDN_P_TE_S0		1
ISDN_P_NT_S0		2
ISDN_P_TE_E1		3
ISDN_P_NT_E1		4
ISDN_P_LAPD_TE		0x10
ISDN_P_LAPD_NT		0x11
ISDN_P_B_RAW		0x21
ISDN_P_B_HDLC		0x22
ISDN_P_B_X75SLP		0x23
ISDN_P_B_L2DTMF		0x24
ISDN_P_B_L2DSP		0x25
ISDN_P_B_L2DSPHDLC	0x26
/*
 * those two are present in include/linux/mISDNif.h but are not handled during
 * socket creation.
 */
/* ISDN_P_B_T30_FAX	0x27 */
/* ISDN_P_B_MODEM_ASYNC	0x28 */