我正在尝试通过 ppp 设置 SIM7000E。SIM7000E 通过微型 USB 电缆连接到 Beaglebone 黑色。Beaglebone 使用 5.10.168-ti-r71 内核（Debian）。SIM7000E 驱动程序已成功安装，ppp 也已安装。
我进入目录/etc/ppp/peers，复制文件提供程序并将其命名为 gprs。Gprs 文件如下所示：
example configuration for a dialup connection authenticated with PAP or CHAP
This is the default configuration used by pon(1) and poff(1).
See the manual page pppd(8) for information on all the options.
MUST CHANGE: replace myusername@realm with the PPP login name given to
your by your provider.
There should be a matching entry with the password in /etc/ppp/pap-secrets
and/or /etc/ppp/chap-secrets.
user "myusername@realm"
MUST CHANGE: replace ******** with the phone number of your provider.
The /etc/chatscripts/pap chat script may be modified to change the
modem initialization string.
connect "/usr/sbin/chat -v -f /etc/chatscripts/gprs"
Serial device to which the modem is connected.
/dev/ttyUSB2
Speed of the serial line.
115200
nocrtscts
debug
nodetach
ipcp-accept-local
ipcp-accept-remote
Assumes that your IP address is allocated dynamically by the ISP.
noipdefault
Try to get the name server addresses from the ISP.
usepeerdns
Use this connection as the default route.
defaultroute
Makes pppd "dial again" when the connection is lost.
persist
Do not ask the remote to authenticate.
noauth
然后，当我尝试通过键入以下内容来调用 gprs：pppd call gprs结果是这样的：
Script /usr/sbin/chat -v -f /etc/chatscripts/gprs finished (pid 1186), status = 0x0
Serial connection established.
using channel 2
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB2
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xf0cd2f0e> ]
rcvd [LCP ConfReq id=0x4 <asyncmap 0x0> <magic 0xd0a7832b> ]
sent [LCP ConfNak id=0x4 ]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0xf0cd2f0e> ]
rcvd [LCP ConfReq id=0x5 <asyncmap 0x0> <magic 0xd0a7832b> ]
sent [LCP ConfAck id=0x5 <asyncmap 0x0> <magic 0xd0a7832b> ]
sent [LCP EchoReq id=0x0 magic=0xf0cd2f0e]
sent [PAP AuthReq id=0x1 user="myusername@realm" password=]
rcvd [LCP DiscReq id=0x6 magic=0xd0a7832b]
rcvd [LCP EchoRep id=0x0 magic=0xd0a7832b f0 cd 2f 0e]
rcvd [PAP AuthAck id=0x1 ""]
PAP authentication succeeded
sent [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 ]
rcvd [LCP ProtRej id=0x7 80 fd 01 01 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]
Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 ]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 ]
sent [LCP EchoReq id=0x1 magic=0xf0cd2f0e]
IPCP: timeout sending Config-Requests
IPV6CP: timeout sending Config-Requests
sent [LCP TermReq id=0x2 "No network protocols running"]
sent [LCP TermReq id=0x3 "No network protocols running"]
Connection terminated.
Modem hangup
我不明白问题出在哪里。有人能帮忙吗？